Had my cambelt changed 2 weeks ago and my car is fine. I did tell them however the car was mapped (went to them in Revo stock guise) and that no ECU updates were to be applied. To be honest if you haven't told them the car was mapped and not to update the ECU I don't think you can complain really. A good dealer will apply any ECU updates when in the workshop, so you cannot fault them for that.