Refund

I went to buy groceries at Pick and Pay Beacon Bay East London. I tap my card for payment, and I was told it's declined. I inserted The card to the machine and put my pin the payment went through. I realized when I check on the bank app that I paid twice. I called the the store to allert then on the same day. They indicated that it will be reversed I should give it time until the next day. It did not reverse on the next day and, I called them again. I was advised to bring my bank statement so that they can look at it. I bring the bank statement and I was told that it is late their payment is already closed, I should leave the bank statement and they will call them the next day. Now I just received a call from them requesting my full card number so that they can release the funds to my account. I just cannot give my card number to anyone. I am told that that is the only option to get my refund back. I just cannot understand that they cannot refund me using the account number., or cash