I'm halfway through my 24 month contract and I've read conflicting reports say I can downgrade and others saying I cannot.

I'm on Dolphin 40 with 1200mins (which I barely use to be honest), 'unlimited' texts & data. Ideally I'd like to get out of my contract, but can't afford to buy it out.

Any ideas what the lowest tariff I could get would be?

Phone customer services and ask them and they will be able to put you on it straight away.