I have done this previously, reduced my bill to £6 a month for 10 months, with 2 months at £20. I got into my 11th month, and the £20 charge came out the bank. I then went on their chat facility online to enquire when I could give them my 30 days cancellation notice, knowing damn well I was 2 months off.
Told them I did not watch Tv enough to warrant paying £20 a month, and could get a better deal using now tv entertainment bundle (same company never the less) so I was looking to cancel when the opportunity arises.
Stuck to my guns for a while playing hard ball with them, then eventually came back with a £5.65 a month offering for 10 months, with the final 2 months being £20.
They credited my account of the previous £20 I paid, so only basically paid the lower rate for only 10 months, and they started a new 12 month contract from this date forward.
The original bundle allows you to pause, rewind and record TV.
Have use of catch up tv.
Channels such as MTV, Comedy Central, sky one, sky Atlantic, sky sports news all come as standard.
So actually a better deal than now tv, more channels, better usability, and only £5.65 a month!! I'll be trying the same trick 10 months down the line 100%!!
Let me know how you get on, existing customers usually get shafted, seems like they don't want to loose customers after all.