Im afraid i cannot offer any numbers that will direct you straight to the UK.  As suggested, ask to be put through to the on site escalations team, when you get to them explain that you have gone to the small claims court and OFCOM and they will then speak to there team manager and should be transferring you to the HLC team.  TalkTalks policy is that if anyone has threatended legal action or has already gone to OFCOM this should be dealt with by the HLC team.

It may be worth sending an email to support AT talktalk.net asking them to record an alternative contact number for you on the notes on your account.