As a long standing customer of Pipex, I'd have to say that Customer Service in general, is not what it used to be. That's before you take into account their aggressive "traffic shaping / management" policy, which is not really (at all!?) explained in their current terms and Conditions.
A shame really, as otherwise my connection is / has been rock solid. To be honest, I can't really see the point of "up to 8mbps" when Pipex don't let you use it (IE. you get throttled down to as low as 20/25KBps and that's not just P2P stuff).
I shall myself be leaving Pipex once my current 12 month contract is up.
Unluckily I suspect this won't be your last problem.