Sprint PCS sold me phone that does not work in my area, Internet

I have been having many issues with Sprrint PCS lately. I was recently shipped out a brand new device that I had to pay for. I was told that due to my old LG Optimus S being a older device I was unable to get decent signal. So I bought a HTC Evo Shift 4G. I was told by the account services rep that was selling me the device that "You will get excellent service in your home area with this phone." When I activated the device on July 14 the HTC Evo shift had horrible signal and was worse than my old LG. Due to service outages with sprint in my area I had let it slide until the issues were fixed. After I was told that issues with the network were solved I am still having issues.

So I called into Sprint Customer Care and was transfered multiple times until I spoke with a gentleman from tech support. He informed me that the type of phone I had was unable to pick up signal in my area. I then told him what I was told when I bought the device. He then stated that there was nothing he could do and I was stuck with my phone that I paid $400.00 for and to get a phone that worked I must pay full price for that phone as well. My question is why did the rep that sold me the device inform that it would not work in my area? Also why does Sprint.com sell this phone on their website for my specific area? I believe that they should not be able to sell and say that these specific devies in area where they will not work!!