Dischem: substandard goods and despicable customer service

I purchased an Biogen Exercise ball from Dischem at Mall of the North which I only opened about 6 weeks after purchasing it. I have a home gym where I keep my exercise equipment which is where I kept the ball, in its box until o opened it. The ball comes with its own pump which I used to inflate it. The ball burst. Not having a chance to return it immediately, I took it back to the store for a refund about a week after having opened it. They refused to refund my money or even give me a voucher for the amount, saying that because the ball was “dusty”, it was possible that I had left it in the sun! Dischem’s treatment of its customers is despicable. They had imp**** that I left the ball lying in the sun and that is the reason it had burst. So, not only do they sell substandard goods, they cheat their customers of their money,and on top of it they shamelessly ********ize their customers. I am a regular customer at Dischem but I will never shop their again.