@fify-- I know what you mean! Even with merchants that have a specific refund policy in place, there can be exceptions made to it, especially if it's a sale.
I once shopped at a clothing store and later wanted to return a shirt because it was too small for me. I had the receipt and hadn't even removed the tag. But the store refused to accept it because the shirt was sold on sale and they were not accepting returns for them. But they never said this to me while the sale was going on!
I guess I should have complained about it but I didn't know how and to whom.