Refund/ Double Billed

Wonga double billed my account and now refuses to refund me. After sending through my proof of payment I called back and was told it was received, sent through to the finance department and will be paid within 48 hours. None of this happened. I wasted additional airtime today and was told the best that they can do for me is email their finance department and wait. Apparently they are not allowed to call out to them. This is affecting my life. Very unprofessional and disappointing.