Orange mid contract price Hike

I've had another letter from orange saying they'll put my contract up.

IMPORTANT CHANGES TO YOUR ORANGE PLAN

We are writing to confirm the details of the RPI price change to your monthly plans, which will take effect from May 28th. RPI (Retail Price Index) is a measure of inflation, which affects the cost to run our service.

I've been on contract over 1 years. i'm on a two year contract, this is the second time they put the price again. the first time i had only been with them a couple of months. How can i get out of Orange EE contract? I can't afford another 2.7% rise. I think its disgusting all the money they make on overcharging as it is. this will be a over 5.4% higher than when i signed the dotted line. i will be speaking to ofcom about this. So anybody got an idea on the cheapest way i can dump orange?