Online purchase refund

I am so disappointed by the pick n pay online services lately. I used to receive my refunds if a product is out of stock, however recently I made 2 online purchases and there were items that were out of stock and when I send them an enquiry they say my bank is suppose to release the refund. When I contact the bank which is old mutual they say the merchant must contact them. I have been sent back and forth and now I am fed up. Since the 24th of January till today I have not received my refund, so disappointed in the services.