I had an unfortunate incident yesterday in my work's car park. My car wouldn't start so I had to push it back to get the start leads to the engine. When I was getting pushed back my brakes didn't work and I pulled up the handbrake too late. As a result I bumped into a girl's Volkswagen Polo and dented her front left-side wing. So I went back into work and asked at reception whose car it was. They made a call on the radio and the girl came out. I showed her to her car and described what happened. I said I would pay for the costs rather than going through the insurance.

She then pointed out some marks near the headlight which had red paint and claimed I did that also. My car is silver and so is hers. She had a few bumps all round the car and scratches. She went on to say her father works in a garage and that it would cost £600, and she would take it there in the morning. I wasn't in the mood to argue and was waiting for her father to say it would cost £100/150 max. So I saw her the next day and she said her father told her to go to another garage in which they said it would cost £500/600 and she wanted to go through insurance. I know this is a lie and she must know someone within the garage who is going to pull a fast one. So I don't know what to do now.

The accident happened in the private work car park. So am I even liable? Also I want to pay rather than lose my no-claims bonus, but I want to pay for the damage I actually caused. I have an independent witness also if needs be, who was going to help me start my car using his car battery. There was no one else around at the time.