Have Toyota Questions? Ask a Mechanic for Answers ASAP
Thanks for posting your question
The first thing to do is to get a written report from the mechanic you took it to stating that the transmission has a serious problem and may need to be replace or at least repaired, this usually stated on the repair order that should have been written when you took the car there, seconds step is to contact the dealer that sold you the car and ask if they have some sort of warranty ( most used car's are sold "as is" so I doubt that is the case. But in most states there is an 'implied warranty', for example;e if you buy a car and it breaks down on the way home from the dealer there is some responsibility on the dealer's part to make it right or refund your money because of a reasonable time clause which in most cases is about 30 days. It all depends on the law in your state.
So as I said, contact the dealer and let them know and ask what they are going to do about this, you have to give them an opportunity to either fix it or give you a refund.
If they say no to either then you can either get an attorney or have the other shop fix it and try to recover your expense in small claims court or just take them to court and sue for a refund of the purchase price, I believe in either case the judge is going to side with you.