Appalling service

My rating is purely for service and not the product itself, as the product is excellent. I recently purchased a pair of sunglasses which was on sale from this supplier on Cyber Monday. When i received the product I realized the colour was not what I expected. I then contacted the sales person a day later to ask for an exchange for a pair in the same price range just a different colour. The lady called Melissa then explained she can refund me and if I want the pair that's a different colour I must pay full price. I then explained that doesn't make sense as the pair I want to exchange it for was also on sale for the exact same price. She went on the say that the sale is over and that all merchandise is full price. I was really disappointed with the service as I cannot understand what is the issue. From a business perspective it doesn't make sense, as they will still get the sale, as I don't want a refund. If price is the issue then my sunglasses are also full price value now too... So in essence a exchange can be done as my sunglasses are also full price and the same value as the one I want it exchanged for.