Cash Crusaders

I went to your cash crusaders store in Nelspruit Mpumalanga I bought an Xbox UFC game when she opened the game it had a loose staple in the cover which I pointed out to her, she said it's fine if it doesn't work bring it back with in 48hours, I took it home the game does not want to load and keeps lagging I phoned the store the following day and told them this and said that I am unable to bring the game back because I'm working out of town and by the time I get back the store would be closed, so I'm calling to inform them of the issue they said it's fine I can bring it back, I go in to the store yesterday 14/10/20 and they refuse to exchange it, saying that the system won't allow it I want another game and I was even willing to pay the difference but they still refusing to help me, what I don't understand is why didn't they tell me this when I called I would of gotten my friend to go and exchange the game for me had I known this was going to be the issue why did they tell me it's fine to bring it back.