...to say that you do not agree to the change in pricing due on 1st May 2014?
I have been a customer for a while. I negotiate a new contact every year/18 months depending on what we have agreed and have a very good deal. Last time was at the end of January 2014 and I got a very cheap deal for my phone and unlimited broadband (less than £2 per month) and a reduction on my line rental for paying a year in advance and agreeing to a 12 month contract. All good.
Today I got a letter through the post informing me that my package now comes "with TV included" and "free phone features and unlimited broadband" but my phone and broadband package will now be £8.50 a month.
I thought this was probably a mistake, but having had them try to wriggle out of a contract mid-term before I thought I'd better give them a ring. Apparently they are putting up the price, but it's ok because I can leave without penalty 
Well no, actually that's not ok. We had a contract agreed only 2 months ago and I do not agree to the change in terms. I don't want their TV package either.
I got a load of guff about how would they make any money if they didn't increase prices? etc etc. I pointed out they are free to make changes to the contract at the end of the term, not during it or what is the point of a contract?
Any hoo, long story short I got my contract left alone. They agreed to apply a credit to my account after I explained that I would not consent to the change in the contract and that if they did make the change I would likely make a claim for breach of contract.
I suggest you also refuse the change if you have a current contract. Mine was just a small amount each month, but for some customers it will be a few pounds per month and up to 17 months. Multiply that by the huge numbers of customers affected and it is quite the con money maker.
Disclaimer: I am not a lawyer. I understand OFCOM have said price increases during the term are ok if customers can leave without penalty. However, the addition of the extra services plus a price rise suggests that this is not just a price rise but a fundamental change of the contract as agreed. I think it's worth a punt giving them a ring because you won't be worse off.