deposit not refunded

i received a rental from avis which i used. it was returned ahead of time with a full tank of petrol. it has been two weeks since the vehicle has been returned but my deposit has still not been returned. i have made numerous calls to the call centre but each time a poor excuse was used for it not being done. it has now even passed the time they have allocated to it. and still no refund!!

#paybackthemoney

sajid