Opel Service Overcharged Us, Which Has Damaged Our Confidence

This is incredible! We left our car at the Antoto Antalya service station. They called during the day, quoted a price, and then offered a discount. When we arrived, however, they charged us over 6,000 tl more than agreed, claiming a dispute and refusing to issue a refund. My father, brother, and I all drive Opel vehicles, and we have complete faith in them! The car was still having the same problem. Never take action or give approval unless it is in writing. Unfortunately, we can no longer put our trust in such a well-known company. Our faith has been shaken. This type of deliberate customer loss is unacceptable. When I called to report the ongoing problem, they never answered the phone. They did the same thing to my father, blaming him for user-related problems and charging for repairs, but he is still unhappy with the outcome. There is no customer satisfaction survey. To say the least, it's disheartening.