Need urgent help topic used car warranty

Hello, I really need some tips from you. I bought an Audi A3 from a used car dealer 2 months ago. So I had the car just a month ago I had problems with the automatic transmission. On the instruction of the dealer I left the car check in a workshop and a transmission damage was detected. The costs were of course too high for the dealer. Then he brought it to another workshop. All good and nice after just under 1 week I was able to pick up my car again. Now the big problem: On the same day the problems started again and much worse than before so that I thought the gearbox was flying around my ears. Of course I called there immediately and told him about it. He thought with a transmission oil change it was okay again, because the specialist workshop could have been wrong with the transmission damage. My question is now I can demand my money back? Or is there any other right the i Because I gave him the chance to have the car repaired, and I’d be happy to have your help, and I’m sorry for so much text.