2006 Volkswagen Polo Recently Had Major Service Done On Car Visting Locally

I recently had a major service done on my car. I was visting and it was not done locally.I drove about 540 km with my car and the only problem i could pick up was the timing was slightly out. I then decided to take it to a local dealer to set the timing properly. They cont me during the day and informed me that there was a pirate cambelt on my car fitted and that causes the problem, they asked my permission to fit a new belt and it was done. The following day i recieved a call and was informed that my valves had bend. I was very shocked.Is it possible for a car to drive 450+ with bended valves. It cost me a lot of money and i dont understand how can you still drive with a car in that state. Can it be?