Avis rips off people

I had a rental vehicle from Avis in Strand, Western Cape. The vehicle was returned cleaned inside and out because i know them. It has been now two weeks and they still have not refunded me, i called them and they have told me they will not refund me the full amount because the vehicle was not cleaned and the the vehicle was not filled up as well. Avis is a total *******. I will never use them again or advise people to make sure they don't bull**** you like they did me.