Total incompetence

I bought Tshirts at Markham, eshowe branch late last month. Today I went back hoping to return and get a refund, in complete compliance with their return policy that is printed at the back of the slips issued to me when buying the Tshirts. To my shock I was told that I wasn't allowed to do so and I was told that the slip they issued to me is a slip from Sterns and the only they were responsible for was the front print of the slip. If anyone reading this is mind boggled at such incompetence that makes zero sense, well, I am too and I was there at the store being told this. Not to forget the smug arrogance from the cashier while I stood there.