When my 12 months was up, I wanted a new phone. I rang O2 and told them I wanted to cancel my contract as it was costing too much per month. They bartered with me and I ended up on the same tariff for £6 a month with a £75 resign credit, which basically meant free rental for 12 months. I told them to keep the £75 and put it towards the cost of an upgrade, which they agreed to.

I got a new Sony Ericsson phone plus a £6 a month tariff and I only had to agree to sign up for 12 months and keep all the existing rates and tariffs.