Volkswagen DSG Transmission Fault

I've diligently maintained my Volkswagen vehicle at the authorized service center since day one. I recently had an automatic transmission problem, which prompted me to take my car to Volkswagen Avek, the authorized service provider. They refused a goodwill guarantee for the repair, instead quoting a staggering 55,000 TL, not including labor costs. Surprisingly, they collected 1,500 TL without repairing anything. DSG automatic transmissions are notorious for having persistent problems. Authorized service centers usually provide goodwill guarantees and free repairs for well-maintained vehicles. So, if goodwill guarantees aren't honored, why do we choose to have our vehicles serviced at authorized centers? I'm left feeling completely let down and wronged. I'm looking for a resolution to my ordeal and would like the repair to be covered under warranty, as it should be.