Avis tries harder. ***??

Hired car on 26 November 2018. Paid for windscreen damage waiver. Returned car 16 December 2018. Small stone chip on windscreen. Up until now still waiting for final invoice and refund. Avis say they are charging me for chip in windscreen. Phoned numerous times. Still no resolution. Avis tries harder to **** off it's customers and succeeds admirably. Use another hire company. Any other hire company. Why on earth does Outsurance recommend these idiots?