Please help with confusing Sprint stuff!!!?

I upgraded at sprint and got a new phone about a week ago. Well I wanted a different phone so I took my new phone back and got my money back so I could get the Rumor. I went online to buy the Rumor and it says that I have to pay full price because I upgraded my phone recently instead of getting the instant savings that I expected. My question is even though I took back my new phone and got my money back does that still affect my account as an upgrade? Is that why I'm going to have to pay $279.99 instead of the $49.99???? I'm so confused.Thanks!!!!