Econo Auto Painting & Body Works

Paint peeled off in a couple months of a car door.
Came back as requested by manager when they are not so busy, the new manager wants more money
payed $462 (contract # WD-XXXXXXX, 08.22.2017, cash only accepted!) to repaint and hang new door(that we got shipped to the shop) on my Ford Focus 2014 and to fix and match paint on a scratch adjacent door. In a couple of months noticed the new paint started to come off and the gray color spot of replaced doors appeared. You can clearly see that the spot is not sanded at all. At first a thin hairline appeared and then paint started to sag. My wife topped by at the Econo Paint shop and the manager looked at the doors and the contract, apologized for bad paint job and told they will repair mistake, they clearly missed the sanding part on that spot. He also asked very nicely for my wife to "come back when they are not so busy, after holidays, if I we live with it". She agreed. Stopped by again after some time and talked to new office employee about it. They were still very busy, "they will fix it if I can wait".
This is my only car to drive my child to school, my wife to work and is used for my work a lot. So we can only survive without the car when we leave town. So before my next vacation We went back for the third time, to the shop and asked to repair their mistake again. The office employee told us that that manager is no longer working "one of the reasons being, that he told people just like us, to come later, when their workmanship warranty expires". He also could not understand why we were charged so much for such a small job! He started explaining us that the prep work is always checked by the manager and then paint is applied, so there is no way the workmanship is a culprit off peeling paint. You could touch the peeled of part of the door and it is not sanded at all. I asked what about paint warranty plaques that are hanging on the wall advertising 2 and 3 years. He said that my paint is even better, but did not elaborate.
He said that they will redo it and went to find a new manager. The manager came in (don't remember the name, Asian descent with an accent and said that I have to pay an additional $100 to get their mistake repaired! It would be $562 for repainting a door, and matching a paint on the scratch of next door - this is absolutely unacceptable. How can they just lie to people like that? They repaint the whole car for $300, that what they have on their reviews. I feel ripped off and being lied to.