Thanks to everybody who offered advice on how to resolve my problem with BT. Much to my amazement, and probably most other people's, I seem to have won.
However, I'm now doing battle with my new telco, Localtel. They seem to be the most incompetent bunch of people on this earth (unless you know better). They ignore my letters, they cash my cheques but don't credit my account, they sign the letters that they do write with scrawled gibberish and so on. Has anybody else had problems with them?
I'm also considering having another go at Tesco's, the supermarket. They sold me a jar of pasta source labelled "Original Recipe". In the corner it also said "New Improved Recipe". I wrote to them explaining that this is impossible, but they just couldn't see that these two statements are contradictory.

Is it just me, or is this misleading advertising?