@roseway, if I'd been up earlier I would have told you that its most likely you are being moved over to Plusnets new network.
Migration to
WBMC Dedicated involves a cease of WBMC shared product and re-provide on to their new platform.
Plusnet will sometimes do bulk requests which is why there may not be anything specific about it that the live support agent could see.
When they first started moving people across, it triggered automated re-provide emails to be sent out to the EU, which obviously alarmed some people, so they have now stopped that.
Mine was done a couple of months ago. Down time was about 5 mins just shortly after midnight.
If you have a dynamic IP, you will likely find it will become a bit more sticky or you will pick up an IP in a very similar range.