Poor quality

I brought a pair of tekkies for my son the once wth shark on, on 20 March i brought it and not even a week it was tearing open on sides,i phoned in to ask if i cn bring it back,i was told i cant because it was worn and it not new anymre .The slip also says it must be in reselleble condition.how cn it be still new and in reselleble condition if it was worn,the time it was brought it was right and suddenly teared open .i had to go to a shoe maker to fix it . that's not how customers should be treated,i wont advice anyone to shop there