Pay back my money

I bought a dress on the 11th at mall of Africa Yde using my debit card,when I get home didn’t fit and went to East rand mall Yde to try to exchange and they didn’t have sizes I returned the dress to get something else where …But my 1199.00 was not refunded I was told the money will be paid into my card in 2 to 3 working days and we on day 4 my money is not refunded..I called the east rand Yde to ask what’s the delay Im told to do a three months bank statement so it can be investigated “like really who is supposed to pay for those statements I really don’t understand your return policy ****py and you just lost a customer..And I want my money back