Cotton on's poor quality and no assistance

I purchased a pair of jeans from Cotton On in Kuilsriver Access Park on the 13th November 2020. I've worn the pair of jeans only 4 times since. And the jeans tore right through in the middle. I returned to the branch on the 28th December to return the jeans for a new one. The manager Gimore came out and told me that there's nothing he could do because it's not a factorly tear. I purchased this jeans in the hopes that it would last me at least a few years and not nearly TWO months. The jeans sold at cotton are expected to be of a good quality and not expected to break and be of no use after 2 months. I paid a pretty price for this jeans and now for what????? I'm extremely disappointed that the branch could not assist me with an exchange. It's not an unreasonable request. The manager Gilmore had an attitude with me and was extremely dismissive and not understanding. I've been a frequent shopper at Cotton On because I love there quality of clothing and it's disappointing that they will no longer have my business. NOT HAPPY AT ALL!!!!!!