Santa Monica Buick GMC

My car had problems with the driver side door not unlocking so I went to the Santa Monica Dealership. After paying $200, the diagnosis was that the "entire door locking mechanism had to be replaced at a cost of $1350". This included $750 for parts and the balance for labor at a cost of $279/hr. Since the door was still working intermittently, I decided not to it fixed at the time. When the door lock stopped working completely, I again called the dealer. Scott, supposedly the manager, said that they would "have to charge for another diagnostic fee of $279 because the first one was done some months ago". When I protested (after all nothing had changed with the car), he backed off but said they would "not apply my initial $200 fee" to the upcoming repair. THis was in total contradiction to what I was initially told (and is the normal policy ). So I left. In the mean time, I watched a couple you tube videos which suggested that the problem might simply be that the door lock pressure PAD needed to be replaced. I immediately ordered it from Amazon and replaced the part. Do you know what this cost?! The part was only $20 and I did not charge for my labor of 20 minutes to install!! The "technician" would have seen the problem in 5 MINUTES and would have spent minutes ..not HOURS to replace a $20 part.