Ridiculous claims from Avis

My firm rented an Avis Hyundai H1 in order for me to go to Bloemfontein. On the way there a stone was flung up by another car and hit the windscreen, causing a chip of about 5mm in diameter. Avis replaced the windscreen and is now charging my firm for the repair. This is the ultimate in pettiness and I have decided that I will not use an Avis car again