That's interesting because I got a text from O2 a few weeks backs (I have a Simplicity sim)saying I had sent over 7000 texts and used over 6000 minutes(can't remember the exact figures)
Then it said don't worry as you are on our unlimited plan.I phoned O2 immediately who looked at my account and said nothing was showing up so just ignore it.
Not had any problems with my account or usage since,but after reading that link it makes you wonder if it was related.
I bet they wasn't British who got arrested