Virgin mobile charged me £170 for 4 calls to 4 different numbers starting 0044795393---- whilst I was in Uganda. Numbers unrecognisable on my phone and unobtainable when I phoned them to see who they were. Arguing with Virgin for over a month and they suspend my phone account without telling me and send snotty letters about Debt Recovery Agency and bad credit rating.(never been in debt in my life ) They just keep saying they are valid charges. A quick internet search found others complaining the same 2 and 3 years ago with T Mobile (funny enough the phone I was using was a T Mobile Zest 2 Black cheapy)
Past links onto Virgin to see if they will change their minds

. http://www.which.co.uk/consumer-rig...ouve-been-misled-by-your-mobile-provider

Might be of help

The big companies do get it wrong.

Good links from granny there.

Sounds like a cloned phone.