Very bad Avis experience

I am beyond absolutely livid. My partner and u have just had the WORST experience with Avis in our lives.

An Avis employee authroized an extention on a vechile, charging an extra R2900 onto our credit card, without verification that it was indeed us calling, other than a surname and car registration details. Surely you have to verify an I'D number or credit card number, legally, approving a charge to someone's credit card?

We now, even though we have returned the car, have to wait a further 10 working days to receive our money back.

Shocking customer care and service Avis.