Shocking service is an understatement

I purchased a backpack at cotton on 4 months ago. Today I had such a. Embarrassing experience being in another store and not being able to pay for my goods because the zipper was stuck so badly I couldn't get my wallet out to pay for my things. I immediately went to cotton on. The assistant manager on duty didn't Apologies for the malfunction or bad quality of the product after I explained my experience. She instead proceeded to rip the bag open leaving only one of zippers now able to close and open the bag with great difficulty. She said they had stock in Different colours but couldn't exchange it as my one was purchased on sale. She then told me I would have to then get another bag ( I've been using this cotton on bag as a baby bag with very minimal things In There mind you) at another store in the mean time them return to the store not to far from today so I could then take soenthing in the shop for the same price as the bag I purchased. The nerve the assistant manageress had to first rip my bag open. Then tell me to get another bag somewhere else then also not Apologies for the defective bag left me quite speechless. This is the second bag I've returned. The first one I returned within a month. The best part is this bag only gets used on weekends and the manager told me that they haven't any other issues with these bags at all. 2 of my friends ds have the same bag one also using hers as a baby bag and hers is fine. I'm disappointed in the product and the bad way she dealt with my situation.