Damaged car - poor service

I took my car to PG Centurion to have my windscreen replaced. I was sitting watching them. The staff kept gathering around my car. I went up to them to ask them if some thing was wrong. They assured me every thing was fine. Before I left I checked the work done. Turns out they had cracked one of the side panels on my car and kept quiet about it. I called the manager who assured me they would fix it but insisted that I still pay my deposit after they had damaged my car. He assured me he would e-mail me confirmation that my car would be repaired. Its almost a week later and I havent heard a word from them. I tried calling 3 times asking to speak to a manager but I was cut off. I took my car to the dealership to have the work that they did checked and the dealer advised that they had not fitted the wipers correctly or the panel below the wipers. And my window now squeeks which it never did before. Poor service is one thing but dishonesty is some thing else!