Sweet talk them and grovel a little, or threaten to leave. I think they will likely waive any fee. I am in this very position, I can upgrade now I have 3 months to run, but they offered me a One X with no fee. But I didn't take it, I am downgrading my contract instead to the to a 1 month rolling contract and will see what is on offer with regards to handsets in the next few months.