I bring good news! I took my (2 week old!) N900 into the my local Nokia service centre and they said they could do it right there in 30 minutes, depending on how broken it is. Mine turned out to be more broken than they could do, so it will have to go back to Nokia, but it's freepost and you literally fill out the form. Apparently it was on a Nokia bulletin in the last few days. I asked about recalls and if anything is going to be done to stop this happening again and they said Nokia isn't just replacing that part. Apparently they've supplied a better designed connector which is being fitted instead. I'm not totally sure what needs to be not broken for the service centres to fix it. As annoying as it is having to send it away, I'm quite relieved that I'm not having to fight them as some people seem to.