The situation is particularly complicated by the bereavement changes. Nominally if you weren't told about a discount being for a shorter time than the fixed term then that can be contested, but it's a whole lot of hassle, and after six months VM usually wipe all call recordings (very convenient, a cynic might suggest) which makes it difficult to prove things.
However, there's a ray of light, of the forthcoming 14% price rise on top of the increase you've just been told about. Why is that a ray of light? Because this year they have to give you notice of this price rise and the opportunity in the next 30 days to cancel or renegotiate your contract. Next year you won't have that option, as the company are baking into their terms a contractual RPI + 4% increase, so VM customers will get notified, but not be able to do anything if they are in a fixed term contract. Moreover, the RPI + 4% will be applied to the undiscounted price, so that the proportionate increase for customers on a discount will be much higher.
As soon as you get the letter about the 14% rise in April and changes to T&Cs, then you're free to act - either to agree a new contract or to leave and take your business elsewhere. If leaving, I'd suggest you consider Zen Internet, as they have no in-contract price rises, whereas all the big scummy corporations are changing their T&Cs to permit them to make this huge price rises whilst ensuring customers can't reject those price rises.
