AAMCO Transmissions review: Transmission rebuild

I took my car in to Amco for a transmission rebuild. I got it out of the shop after arguing with them three times over the prize they had quoted. The shop was completely dishonest with me and did not stick to their original quote and kept adding expenses two different times. I argued with them and brought the price down $500. my car is not running well. When I got it out of the shop, it seemed OK but the very next time I started it there was a vibration and shake. I took it to another shop to get assessed and they said it was the motor mounts. Now AAMCO wants to charge me 500 additional dollars to replace them. I had no vibration in the car whatsoever when I took it in, and they didn’t get the motor mounts aligned, right, and they need to fix them. At no cost.