So far so good... I wrote:

Description of problem:
I can hear someone talking in the background - crossed line? Quiet, but loud enough to hear what she's saying, and it is very distracting to hear someone ordering underwear when I'm trying to hold a conversation.

This has been the case since I got the line sometime in '99, but last time you said you'd send someone, nobody turned up, and since I use the line mainly for internet, I gave up. However, she has a very loud and nasal voice, so I thought I'd try again.

And I got the following reply:

We would like to apologise for any inconvenience you may be currently experiencing. A fault has been identified.

We expect to respond to this fault within/by 1 working day.

Note : You can now receive FREE regular updates on the progress of your fault via SMS text messaging on your mobile phone. Please enter your mobile number in the box below and click on 'Go'

Nice!

Now, let's wait and see if it works this time...