Data roaming is enabled. Both phones have never had a problem with any other provider. I've tried calling the help number you provided but gave up after 15 minutes on hold with no indication of when I'd get through as presumably this was costing me a fortune.
Can someone contact me urgently by email and sort this out please.
Initially the response there was good. Someone got back to me quickly and sorted out one of the phones. Unfortunately the other phone (iPhone) was not fixed and despite numerous attempts to re-contact the team for the last week they now seem to be ignoring me.
In the end I created a second Social Media enquiry and eventually, after a long-winded and tortuous process*, managed to speak to someone in the complaints department.
He couldn't see anything wrong with the iPhone account so all I can do the next time I go abroad is to phone VM before I leave to check the account again and hope for the best when I arrive.
P.S. I note that your Social Media Enquiry page doesn't exist anymore.
* The biggest complaint customers have with large organisations like VM is the inability to contact the appropriate person in a timely manner. If a VM staff member has asked me to phone him it is frustrating that I have to:
1) Phone the general help line and go into a queue.
2) Speak to someone that isn't able to transfer me to the right person and asks me to hang up and ring the same number again.
3) Ring the number again and go into a queue.
4) Speak to another person and explain everything again.
5) Be transferred to another telephone queue for the correct department (who's number is secret).
6) Wait in that queue until someone answers. The agent says the person I'm contacting is free so they transfer me again to their number (also secret).
7) By this point the batteries in my phone were almost out of power and I can see myself having to start the whole process again.