I received a call two days ago supposedly from Three saying my name and that I qualify for an upgrade. 15 seconds later the call ends mid sentence from the female caller, nothing since. I found a comment online that it could be a scam designed that when you ring the number back you incur a cost. Maybe its just exceptionally bad customer service from Three.
http://ie.tellows.net/num/014866496
http://ie.tellows.net/num/014866496