DO NOT USE AVIS CAR RENTAL

I booked and fully paid for car rental with pick up at the Belgrade Airport. My flight form Jhb to Belgrade was cancelled just before a boarding and I was on the flight next day. I have not cancelled my booking as I needed the car on my arrival just to find out that Avis does not have a car for me. I paid a full amount in advance and there was no car for me. On my return I submitted refund application and after waiting for almost a month without any reply (they promised 7-10 days) I was informed that I cannot get any refund. I did not get the car that I paid for, and had to take another car and pay for it. It was due to flight cancellation that I arrived later then planned but still they did not keep car for me and they refuse to refund the amount I paid. NEVER AGAIN WILL USE THE AVIS!!!!