What to do when you are a promised a research-based research associate role but are required to act in an IT support role?

Your writing certainly does not betray a "lack of eloquence"; in fact, it's probably better than most of the computer scientists I know!

That said, as JeffE has indicated, you are being mishandled by your employers, and I would strongly encourage you to find a new position as soon as possible. However, it is important to point out that your situation is not academic versus industrial, but instead good employer versus bad employer. The distinction is crucial.

In any position, there will be parts of your job that are less appealing than others; the absolute "dream job" which you're happy about 100% only exists in Utopia. The key is to make sure that the important parts of your job give you more satisfaction than the less desirable aspects take away. Here, this clearly isn't the case. That does not mean that you can't find what you're looking for, either in industry or in academia. What it does mean is that you need to find it somewhere else than where you are, because it's clear the job isn't going to change in any sort of meaningful way in the short term.

The answers so far have many good points: you are being abused, you have been misled, you would do well to seek employment elsewhere, perhaps you were not assertive enough, and so on. But I believe none of that matters much compared to your decisions from this point on. You sound like a person who prefers to think ahead and plan important decisions rather than improvising—many researchers are thinkers who want to weigh their options and take their time to come to decisions. If you wish, you may plan for retribution and for taking a fight, but in the end this will not make your current workplace any more healthy for you to work in. I would suggest the following concrete steps of action:

Find the job advertisement you responded to, the written job description, your letter of application with any supplements (even if it was just an email), your employment contract, and any other documents (including emails) that pertain to the decision to accept your current employment. File these together in a place where they are safe and where you can find them if needed. Make copies. Assert to yourself that you were promised something that was not delivered.

Gather the articles you have written or started to write, regardless of whether they are published or not. Also, make a list of other work you have performed during your employment. For example, list the features you have implemented in the software system you described. File them together in a place where you can easily find them. Assert to yourself that you have performed well in your work despite the situation.

Look for a new job that is certain to either include research opportunities or to be totally unrelated to research but limited enough to allow you the mental capacity you need to conduct research on your own. Perhaps this position can be found within your current university, but in another group. Choose carefully and ask direct questions about what is most important for you: "how many days a week will I be able to work on research?", "how many days a week will I have to do overtime?", etc. Ask to meet one or two of your potential co-workers and ask them if they believe you would get what you are looking for. Be friendly and remember it is not their fault your current supervisor is misbehaving. Assert to yourself that you can consider the options in your own time and that the responses to your direct questions are what matters in your choice, not feelings that you are fabricating out of previous bad experiences.

Agree on the date when you will start in the new job, taking into account the conditions of your current employment. When you have signed the contract for the new position, immediately notify your current supervisor that you will move to another job and ask for a prioritised list of tasks that you should complete before leaving. Complete these tasks to the best of your ability and ask for a letter of reference. Assert to yourself that you have fulfilled the conditions of your employment and are entitled to a reference.

If your supervisor asks for a reason for you leaving, or becomes unreasonable, explain shortly that based on the job description, you thought you had a research position but it has turned out to be a technical position. Your supervisor is likely to try to bargain with you, and try to promise you more research opportunities in the future. Don't trust this promise—it comes from the person who misled you and who cannot be trusted. Stay firm but polite and state that you feel it is time for you to move on. Keep repeating this if the supervisor insists: you wanted to do research but the position is technical, and it is now time for you to move on. Assert to yourself that you have no obligation to explain your personal choices.

If your supervisor does not write the letter of recommendation, politely but shortly remind him a few (three) times (do it over email and save the emails), but then let it be. He will owe you one, and if you ever meet in the future, he will be the one who didn't behave properly. Assert to yourself that you have resolved the situation by your own actions and that any remaining problems are not yours.

If you got a new research position, engage frequently with your new supervisor and agree on writing a joint article. Make it something simple that you can complete soon. Focus on getting that article out, even at the expense of other assignments. Then keep repeating the exercise, taking on larger and larger projects, involving other members of your group. Share your successes and failures in your new job with your supervisor and your peers, and listen to their encouragement and advice.

If you didn't get a new research position, relax in your new job. Don't take on new things and just let your supervisor assign tasks to you. However, always carry out those tasks well. In your spare time, you can now complete the work you had started before, and build a small portfolio to support you in applying for a research position. Assert to yourself that you are not going into the game that your supervisor went into—you proceed in your own pace.

The most important thing after getting out of your current situation is not to bring with you any maladaptive behaviour that you may have developed as a result of the stressful and unreasonable environment you have worked in.

Good luck!

You are being taken advantage of.

You should check the rules at your institution relating to authorship. It sounds like you have made a significant intellectual contribution to the papers that were published, so you deserve to be listed on them as an author. There are means by which you can have yourself rightfully listed as an author on the papers.

The practice of more established academics taking advantage of postdocs and research assistants is widspread in university departments worldwide. Your situation is all too common.

It does however sound like that you "walked into" the situation a little bit, and that you should have been more assertive and forthright from the start about your role in the team, your contribution to the papers that were published, and your rights as an author.

You should move on and view the situation as a learning experience for next time, and improve your self confidence and assertivenes.

Btw not sure what not having a wife and kids has to do with anything apart from you are able to take more risks with your career?