We went for a usual preemptive service, the car ha...

We went for a usual preemptive service, the car had nothing wrong with it. We do maintenance on time and always there.
After we left the car had engine light and engine noise. They said it wasn't their fault and that'd they charge to bring it apart just to diagnose...
We replied to their emails for feedback and they just became quiet and sent some generic emails.
Poor customer service and accountability.