Refund and return

I bought a bag from Unze London from sale on allied card And before making the payment, I confirmed with the staff whether this exchange will be returnable and changeable. He said yes, it will be. I said, okay, buy it without worrying, it will be returned and you will also get a different one if you don't like it. And I went to change it half an hour after buying the bag, m saying that I just want to exchange it. They rudely said that they did not change my order, that there will be no return and it will not be refunded.Very pathetic experience with unze london kohinoor City branch faisalabad If they don't have the knowledge, then why do they miss guide me?