AVIS are *******!!!

I paid deposit using my ABSA bank debit card and AVIS promised to release my deposit 14 days later and that was done on the 29th September 2017 up to date (almost 7 months later)my deposit is not paid back into my account, Avis told me that the bank have release the funds, I've sent them my 3 months bank statements to show that funds were not deposited not have miraculously increased my balance due their funds release policy and I've been to the bank to inquire about the funds released into my account by Avis but the bank said there was no such... the funds needs to reflect but nothing still. I am tired always calling AVIS for my deposit. AVIS SHOULD PAY ME BACK MY DEPOSIT WITH INTEREST! avis is ************. I've even returned their cars in full tank but they still charged me refill of more than R350 for each car... claiming they had to refill. I feel very ****** by AVIS!