Poor service from Clicks Eyethu mall

Sent my younger sister to Click today to by Huggies gold and she bought the wrong size and she bought huggies pants on top of that she bought the huggies pants and lost the till slip but swiped for that transaction. we went back asked if we could change them and get the ones that clip on on the side and a proper size which is a a 4+ not a 4 but they refused to assist it wasn't even 24 hours since we bought them we have the sms that confirms the purchase and the bank statement but they refused to assist. :-( now my son doesn't have dippers