Sony Ericsson Xperia X10 :: WORNG MY Phone Numbers

I got my X10 on a new contract (with 3 UK) and got a new mobile number with it. I then ported my existing number over with a PUK code. This took a couple of days, and while I was waiting I mucked about with the phone using the new number that 3 had given me. After the PUK transfer took place, my X10 still thinks that "My number" in the phonebook is the new number that 3 UK gave me, not the one I subsequently ported across.

So, if I go into the phonebook the bit at the top where it says "My number" is wrong. I can edit that default contact, but there's no option to edit the main phone number for it - all I can do is add extra numbers. I've been digging around a bit, and I found the phone number set in Settings > About phone > Status. Again, it can't be edited here. It's also viewable (but not editable) through the Service menu (#*#*4636*#*#). It's not a big deal, but it's annoying because it doesn't recognise "me" in Timescape when looking at messaging conversations with someone (on the Infinity button). So far all SE support have said is the standard "check you've got an up-to-date SIM card" (which I have, and which is what they always say when they're trying to get rid of someone).