Apparently they sent me a letter that increased my charges. It is in their contract apparently that they can increase your charges by whatever they like and you have only 30 days from the time they tell you to do anything about. However the letter they send does not warn you about this. .
They increased my charges for a line by 35% and was stuck with them for another year. Finally leaving and out of contract they tried to scare with claims i owed them £299. With new provider going to be saving over £25 month and will be on fibre instead of normal broadband.