So BT decided to offer me a new deal with the price increases to match the best offer at the time, Infinity 2 and phone for £26.99 a month. Fantastic!
So a week goes by and my speeds haven't risen, strange. So I email them asking why. Response was "sorry, will be actioned in the next 48 hours". I assume you can guess where this is going. The next communication involved them telling me "sorry, your line isn't capable of the speed we said, so we can't offer better, but it's still a really good price so personally I think you should be happy.
Unsurprisingly that comment was one too far, and I've promptly told them where to shove it. Repeated lying about service provision and then being very reluctant to deal with it.
Oh, and my line not being suitable? I now have a 75mbit stable connection with Plusnet. Ironic, seeing as they're a wholly owned BT subsidiary...
Moral of the story, I will never use BT directly again.