Bumped my car - then denied it!!

I was parked at a red traffic light waiting for the light to go green with my hand brake up all of a sudden the car behind me doesn't stop in time and rear ends me. She was very quick to apologise for not stopping in time as she was using her bosses Mercedes which is an automatic and that she is not used to automatics. After giving me the companies insurance details to claim and requesting 3 different quotes to e mail to her I get told the claim will not be paid by Santam as she now denies bumping me<br> And rather that I must have rolled back?!! If I rolled back it would not have caused damage besides my handbrake being up? I am utterly disgusted in companies (especially insurance brokers) that are able to to get away with things like this. I will definitly not be recommending this company to anyone.