Deposit not returned

I tried to rent a car at Avis on the 9th of May, they took the deposit then told me I can't get the car because I was flagged for an outstanding payment from 7 years ago. I then decided to use another rental company while the investigate. I requested my deposit but was told I must wait 5 to 7 days which I didn't understand because I did not take the car so why keep my money. I still don't have my money 14 days later and multiple calls trying to resolve this. Being **** to and given false promises. I just want my money back. The amount I was flagged for was a *****ulent transaction under my name so I should not have gone trough any of this.