If you have moved abroad then using a Pay As You Go Sim won't work for you for long periods of time.
It's meant to be used for short periods ie holidays.
"You can only use our services for periodic travel, like holidays or short breaks, in our Europe Zone (excluding the UK). Otherwise we may charge you for using our services in our Europe Zone (excluding the UK). If this has happened to you and you think it might be a mistake, call 4445 from your O2 mobile, or 0344 809 0222 from any other phone. Use of our services in our Europe Zone is subject to our fair usage policy."
Veritas Numquam Perit