Avis Debiting extra money off my account

booked a vehicle with Avis, gave them the holding deposit with the usage fee. Extended my booking for the vehicle, Avis asked for a further deposit which i had given. the total amount, totalled to lower then the 2 payments i have done to Avis. i was waiting for a refund from Avis to come for the balance. when i looked at my account today, i see that Avis debited a further amount from my account, which is unacceptable. when I phone them, i get absolutely no joy. the stuff are unfriendly and say sorry we cannot help you please phone your bank.

absolutely disgusted.