Lack of assistance!

I wasn't very impressed when I sent in an email inquiring into whether I could make a change to my order as I had seen there was an option to select the size of my rings only after I had finalised the payment. I sent in an email straight after I had placed the order, provided the order number and was told the following morning in an email response that there can't be any changes made, so now I must return the package and ask for a refund and then place another order for the same product in a different size, REALLY, HONESTLY? It's quite ridiculous!