Not impresed with service at Zara Sandton City- A ****

I purchased trousers and paid on the self check out and printed the receipt, unfortunately lost the receipt. The purchase was done with a debit card, when I got to the store I was told the clothes could not be returned/exchanged in the absence of receipt with bar code. To start with the system did not prompt for cellphone number, that I confirmed on the day of return as I purchased new item, the same system did not prompt the sales person for cell number for the digital receipt I am being told about. My issue is that how does a store not have digital print of the stuff bought at their staff with a card. Zara is a ****!!