OFCOM has a lot of rules for ISPs to follow and under General Condition 14 (GC14.5 – Dispute Resolution) – all ISPs in the United Kingdom are required to be members of an approved ADR scheme like CISAS or Ombudsman Services, which are designed to supplement (not replace) the ISPs own internal complaints procedures and are only used after a dispute has gone unresolved for 8 weeks (the “Deadlock Letter” stage).
The ADR process is a very useful tool for consumers, albeit an unpopular one among ISPs (i.e. they still have to pay up to around £350 +vat in fees to the ADR regardless of whether or not they win), but some smaller providers continue to flout the rules by wrongly assuming that they don’t have to offer an ADR or by failing to make customers aware that one is available.
The key here is that if one were to make a request to unblock a website and the ISP doesn’t co-operate then you can start the ADR process.
Upon being told that the ISP won’t unblock the website request a deadlock letter in accordance with the Alternative Dispute Resolution process.
At this point the ISP representative will probably try and convince you that you cannot make an ADR complaint about this as they are scared of costing the company ~£350. Insist on your deadlock
Imagine if everyone with a censored Internet connection raised an ADR complaint for every blocked website.
Choose.net has an excellent guide on how to go about raising an ADR.