Okay. If your case is still pending, it appears your first best step might be to speak with a couple of other attorneys in your area and see if one will take on your case at this late stage, this before terminating the services of your current lawyer. If you do not intend to hire another attorney, though, you could skip right to firing your current attorney if you are unhappy with his/her services.
If there are any steps outlined in your current contract on terminating the relationship with your attorney, you should follow those. Otherwise, you need to notify both your attorney and the court that you wish to terminate the services of the attorney. You can send a certified or registered letter to the attorney advising the attorney you no longer wish to employ him and that he should stop all work on your case. You should request that all of your files be sent to you or, if you have hired a new attorney, the new attorney can ask your attorney for a transfer of all files. The letter terminating the services of your attorney does not have to be fancy and full of legalese. A simple letter sent to the firm/attorney will work.
Here is where it gets tricky. If you signed a flat fee agreement with your attorney, the amount paid is generally considered earned. Your contract needs to be reviewed to see how the fee agreement is worded. Michigan operates a little differently than California when it comes to nonrefundable fees. In California, even with a flat fee agreement, you could be entitled to a refund for services not rendered.
The attorney will need to send you an itemized bill that justifies the amount owing or deducted from your retainer. If you do not believe the attorney has worked toward or completed any or all of the work he agreed to do for you, you can dispute the fee amount.
Here is a link on how you can dispute the fee:
http://www.calbar.ca.gov/Public/Pamphlets/FeeDispute.aspx
What I have bolded of your post quoted above puzzles me a bit. If there is "no legitimate reason to terminate the case," the attorney you hired might have been frustrated in his efforts to satisfy the terms of the contractual agreement he had with you, through no fault of his own. This can be a complication in seeking a refund.
Most lawyers are honest. Most lawyers work hard for their clients. I am not sure what has happened with your attorney or your case.
Good luck.