If I upgrade my US Cellular phone (when I'm eligible) will they also make us restart our whole contract?

Ok so we're (my mom, me, and my brother) a US Cellular costumer and we're now eligible for an upgrade. The contract isn't supposed to end until April of 2014. My mom has a smartphone. My brother and I have the regular old everyday phones. So my mom said that when it was time to upgrade we could get a smartphone.(Could we just change our regular plans to data plans?) Apparently after we talked about getting new phones and all my mom called US Cellular at work and they said that upgrading our phones would also reset our contract for another 2 years. (We don't want our contract to restart because service is poor where we live so we're going to switch when the contract is up.) I think she was lying, was she? (She lies A LOT)

Why would she lie? I'm paying the smartphone myself so it wouldn't be like she just didn't want to pay for one. The only thing I could think of is that she just doesn't want to drive a couple miles to the US Cellular store.
Thanks!