I have recently been running into a strange problem within the last 2 months, I have kept getting these texts 12 days before I am supposed to run out by O2_ saying:
To continue using data in Europe this month it's £2 p/ day for 100MB and will deduct from your balance. This annoys me as I haven't used my phone more than usual and I paid for the whole month and want to use it for the last 12 days.
