Retaining deposit and deducting invoice amount

I have been the \victim"of Avis on 2 September 2015 deducting an invoice amount for a rental early the previous week from my account and this despite still retaining the deposit initially taken. The effect of this is that 7 small debit orders bounced overnight and I got charged R 138 for each bounced debit order (more than R 1000). This is ironically more than the rental. Surely you cannot retain the deposit and deduct the invoice with the idea of only eventually one day giving back the deposit. It should surely be a single transaction. This rental now in effect cost me more than double just because of the untoward way in which you elected to operate. PS I effect rental with Avis on at least a monthly basis and have never before had the deposit retained while the invoice amount goes off on my account. I will def reconsider my future custom."""