Pep Store (Diepkloof Square)

I have been de*****ed of a R1000 flash voucher by one of the cashiers in at store(Pep) in Diepkloof Square. What they do is reprint or take details(pin) of the voucher you bought and send it to one of their friends... I've been trying to get the store to pay back my money for about a week now with no luck. The manager doesn't seem to care as it not his or her business that is affected by this ******** behaviour practiced by his/her employees. I'm certain the cashier in question hasn't been dealt and will continue doing such. This has taken a big knock on my business, please help. Any advice will be highly appreciated.