A warning to anyone who took their iPhone abroad this summer. Even if you turned your data roaming function off in the UK before going, I've heard a good number of cases of erroneous charges when the next bill arrives.
It seems a few phones have had a glitch that means international roaming doesn't turn off properly overseas so apps are still connecting at a cost of up to £8 per megabyte.
So if you have been abroad in the past six months, check if you have been charged unfairly. If you have, contact your mobile provider and highlight your case. Most people who have done this a have been given the excess charges back.
To minimise the possibility of being charged for data on the unawares, also ensure your iPhone software is up to date (when you plug your phone into iTunes you will be alerted to any new software updates, so just follow the onscreen prompts), switch off data roaming before leaving the UK (go to settings > general > network, it is the third option down) and ensure your email is set to retrieve messages manually, to stop downloading emails automatically in case you need to switch data roaming on in an emergency. To use data abroad, try to find a free or cheap Wi-Fi spot.