Avis double debit

I work in a bank and had a client that was very furious with avis debiting his account twice... I have been communication with a lady called Sharon at port Elizabeth airport who's been very helpful and patient with the whole matter. I can't discuss the matter in to detail in this platform but I am frustrated on behalf of the client that he still has not received his money back after two weeks of trying to resolve this issue. I am complaining here so that I can get assistance with resolving the matter asap who ever that can help from avis can contact Sharon in pe Airport she has all the details of the matter as she has been trying so hard to assist me but still no luck. The review is not about Sharon because she has been very helpful but I need help to solve the matter asap please