Originally, Ofcom had said they could change price, but had to let customers cancel at no penalty.
I did extremely well out of that, for a period I was signing up with new broadband providers, getting say £150 cashback, and then a few months later cancelling penalty free after a price rise and grabbing another chunky cashback.
Then they said "actually, if you state a % rise up front, that's OK", and everyone said we'll raise by RPI + 3% or whatever. Then RPI went above 10% and people were getting stung for 14% rises. So everyone kicked off.
And now Ofcom have said "actually, that's too confusing, now it needs to be a cash value", so they're all saying it will go up by £3 per month each year.
Which is alright on broadband, but will suck on things like mobile phones where you might have a £6 contract going up by £3.
As usual Ofcom are just being really reactive, and freaking out when the media declares something to be a shambles.
I don't think there was much wrong with the first system, other than that it wasn't hugely obvious to people that they could just tear up the contract after it rose. At least that carried some risk / reward on both sides.
As far as I can gather the only mainstream supplier not baking in price rises right now is Sky, so I might go with them for my next broadband contract.