AVIS Car rental OR Thambo

Rented a Mercedes Benz C200 Avantgarde by Avis Menlyn on 17/01/2019. Still waiting for my invoice. Contacted Avis customer care. They rep**** two days later and said the invoice is outstanding due to damages on the left tyre rim. The vehicle was just used to drive to the airport and it was inspected when I returned it. Was not in any kind of accident or anything. This is the second time this has happened with me. The prvious time was approximately two years ago with a similar vehicle. Avis at that time just deducted money from my credit card for damages and it took me two weeks to get my money back. They finally realised it was a mistake on their side and reimbursed me. Tried to phone them for 5 hours today. no one was able to help me and they don't respond to emails. Absolute pathetic service from them. Already waisted more than R 300-00 on calls today as I am phoning from abroad to resolve this issue. Very disappointed in Avis. Second time this is happening and it is not acceptable. Can someone who is capable to handle the query please assist. The staff at OR Thambo are not capable to perform this task and they never answer the phones. Please help