As promised, I've written a script which generates DPA Section 11 ('No Marketing') Notices for BT/Virgin Media/TalkTalk.
A Data Protection Act Section 11 Notice instructs your ISP not to use your communication data for personal marketing.
Simply select your ISP, enter your account number, name, address, click submit... and bingo, a DPA section 11 notice to print and post. The text is derived from the
ICO suggested wording for DPA section 11 notices.
http://www.dephormation.org.uk/dpa_notices/
All you need is an envelope and a stamp.
On a related note, don't forget you can also generate a letter to your MP using this script;
http://www.dephormation.org.uk/letters/