Avis Pretoria branch does not want to pay my deposit.

Non refund from Avis Pretoria branch, the branch is withholding my refund because of a small dent in which I took super weaver to cover that but I am still told I am charged liability of R5800,I asked them how much was charged for the dent as I do not expect it to be over R1000,The are not answering their phones or responding my email and I am unable to visit the branch as I am out of the province.