Unauthorised debit order

I opened and account with Afrox for the supply of oxygen for home care. I was told to pay an amount of R779.04 before the oxygen tank together with the oxygen and mask will be delivered. I then paid that amount. The tank was then delivered. On the 02nd of June Afrox debited my account for that amount. I queried it with them and they told me it was a mistake and they will refund the money. Today is the 12th of June and I still have not received the the refund. Please refund my money