Greenbelt Capitol Cadillac failure to diagnose timing chains engine problems Greenbelt Maryland

 the Cadillac SRX 2006 is known to have a timing change defect. Greenbelt Capitol Cadillac has been the dealer who did the major maintanence on my car after purchasing the vehicle used. Yet, my oil changes were performed at other facilities -local reputiable oil change facilities . The vehicle was taken on several occassions, to the dealer for concerns related to noises heard, the last 1/2013 and the bill from that visit was 2200.00. Yet in June began to have the same problem yet more intense. Dealer attempted to blame me, the customer for failing to get oil changes. therefore they wanted to charge 2300 to fix the problem.  I was asked to bring in documentation to prove the services (oil changes) had been performed. After discussing with the dealership that oil changes had been performed ( faxed over documentation), they then decided they would not take the responsibility for the problem that they knew existed. I researched on the internet which had reviews from many customers with the same problem. I do not understand why the customer must pay for the failure of dealers, multimillion dollar corporations to take responsibilities. Yet, why they (the dealerships) feel they can treat faithful customers in such a manner. I will never purchase another GM vehicle