Avis consultant mis-leading infomation!

05/12/2015 we hired a vehicle through Avis via our insurance broker Compendium -we were involved in accident 04/12/2015. We were assisted at Umhlanga branch a consultant who explained the 1 way fee as we would be going home to Johannesburg, not returning to Durban. He explained the insurance and liability amount which we were both happy with. Consultant explained the windscreen cover- which I discussed with my husband and we both agreed it would only be necessary for one day. The amount he said was about R35 a day and would be charged to the same credit card we used for the deposit. The risk of a stone chip on the open road home was more likely than once in Johannesburg on local roads. After a few days returning the vehicle my husband requested the invoice. We have been charged for \windscreen tyre damage waiver\" an amount R610.45! upon enquiry the manager took 2days to come back to us only to say