Mr Price Gift Voucher Rip-Off

I ordered sports gear on Mr Price Sport via their App on the 7th of January 2019 and was expecting delivery/collection within that same week however when I enquired about my order status they advised that my order was not placed and they requested my POP to which was provided. Today on the 14th of January 2019 I was informed that the items I ordered were out of stock to which I opted to cancel the whole order and get my money to the value of R649 to be refunded. They advised that since payment was done via EFT they would send a gift voucher, to which they did however the value of the gift voucher was R299.98 to which is not even close to the money that I paid for the items.... May I please get my full refund back,