Tobra has sound advice. I agree with him.

To be absolutely blunt, a "mechanic" who can't diagnose the problem, gets frustrated easily and doesn't communicate honestly with his customers should find another line of work. Short of purchasing a used transmission and installing it -- at no additional cost to you, I'd refuse to let him touch the car. h:

I certainly hope you have documentation of all of this; the work order, your reciepts and notes about the faliure to correct the inital problem. IMHO, you should not be doing his work in trying to diagnose this problem. You've paid dearly for his services already - you are entitled to a properly functioning car. It seems to me that this "mechanic" is incapable of doing that.

Unless he scares easily, the time is coming to [litigously] lock and load..