It looks like a Geographic number for Newport Wales, BT has held the number block since 1994. Not sure how you could be charged "extra" for this. Look at your phone plan for the cost of "geographic" numbers.
On a side note, this number looks to be used as a telemarketing/possible scam phone number. If your getting lots of missed calls from them I probably wouldn't phone them back.
---- I do not work for VM, but I would. It is just a Job. Most things I say I make up and sometimes it's useful, don't be mean if it's wrong. I would also make websites for them, because the job never seems to require the website to work.