Worst service ever

I am really disappointed on how rhwy dealt with the of full tank. I returned the car on full tank, and I was also charged for another full tank at OR Tambo International Airport Avis. Tried to explain but I had to accept the charge due to unfair explanation. I then returned the car and my deposit was still not returned the vehicle. I visited the branch to confirm if the deposit had been released and they said yes. Further asked me if I did not extend the rental and I responded by saying NO. Someone is not doing the job and end up frustrating us as clients.I then approached the bank . The bank indicated that AVIS is still holding the deposit and need to seek assistance from AVIS to release the funds, I'm not sure why AVIS has not done anything to date.

Am starting to be frustrated