Shoppers Drug Mart complaint: Idiots

Hi, I recently bought a perfume sample set from shoppers but realized later that I bought the wrong one. I intended to buy the delux perfume sample set. The shoppers that I bought it from was not as close as the shoppers mentioned above. So of course I went to the shoppers that was convenient to do the return, mind you I bought this one week ago. The product is still sealed in perfect condition. I had the receipt and card ready for the refund…. I got to the counter and asked if I can exchange it for delux she said it’s out of stock.. then I said please refund this and I will purchase online.. she told me to go back to the store I bought it from…. because they are out of stock .. it doesn’t make sense what would stock have to do with my wanting to return my item, why is this a thing ? I told her that it’s far and inconvenient and she told me she couldn’t process me return.