Pipex - Can they hold me to contract

I moved from Pipex Xtreme Solo to Pipex Midi but I certainly regret it as it has been a awful experience of slow connections since. I've tried everything their tech support have suggested to no avail and I've just rang to get a MAC code only been told I signed up for another 12 months by changing service. Can they hold me to it since basically I've not been getting the service I expected.

That would depend on when you "changed" service and just how bad it is. Do your Ts&Cs not help at all?

If you have kept the times / dates , names of person and what was said for all your communication with Pipex you have a good chance of terminating the contract for free especially if they told you to change package to improve the service. If not starting from now ask them to fix the fault and collect as much info as you can. If like before they continually fail to fix the fault and let you down you can then negotiate with then to release you free of charge. Make sure at all times you remain calm but firm and keep in mind that they may fix your fault but if not then tell them to release you from the contact you were falsely sold.