Avis refuses to give back my Deposit

I was involved in a car accident about a month ago, my insurance gave me a courtesy car, for some reason, i was asked to pay a deposit , some sort of insurance thing.i did that, I was told that i would, upon returning the vehicle undamaged, receive back the deposit within 72 hours.Now , me believing that Avis is a well known brand and a reputable supplier, i had no worries about this. so i returned the vehicle to the East London branch as agreed and it had no damages.i left, three days went by, nothing.a week went by, I called, ad a gentleman by the name of Nazeer assisted me and said he was going to forward my number to Head Office so that my payment could be throughout called about 5 times in a week and needless to say that 3 weeks later i'm STILL awaiting my deposit, they all say they will get back to me , i called now and spoke to a Siviwe who then said they would call me back.in this day and age of the declining rand value, R2100 is a heck of a lot of money...Avis IM VERY DISAPOINTED