Attitude from store manageress

My mum went to Mr Price Sport on Saturday, 27/04/2019 to return a wristband which had been purchased. The problem we are having is that the wristband is made of a poor quality. I did change the on 13/04/2019 as I had the problem where the cotton had been fraying. I was given another wristband and thought maybe it was an issue with that set of wristbands. A week later the same issue occurred. My mum went to the store and the manageress stated that it cannot be changed as it had been used. She did state that it has been used and asked my mum if she would buy something that was used. Then the manageress stated that for 13 years or so she has been working there she never had any customer come back to her with the quality of the items sold at the store. Is this how the Mr Price group treats customers? I have bought shirts from Mr Price and after a few washes the collars get all creased up. I can buy the same shirt at HUB for almost the same price and it was last me longer. My mum had proof of payment (emailed receipt) plus we had the original packaging so why does it have to be such a hassle to get something resolved