Poor customer service - problem could have been handled EASILY

Ordered box of (expensive) personalized Christmas cards on Saturday 11/14. During order process browser refreshed, knocking out some of my info (included quantity.) I didn't realize until after I finalized order that I had ordered ONE box and actually needed TWO. E-mailed company to have another box (OF EXACTLY THE SAME THING) added to my order. They said that it wasn't possible. Keep in mind, I wasn't asking for a change to the cards, just an extra box. They had the opportunity to make additional money off me and keep me as a customer. Rather than provide any customer service decided it would be better to pass on the money and make a first-time customer an ONLY-TIME customer!