I'm sorry that you're having a problem with your data roaming service. Have you logged into your Mobile Online Account and verified that your roaming service is switched to ON and International Call Barring is switched OFF?
Please verify that your data roaming setting on your mobile is enabled and that your APN settings are correct as noted on this post: Roaming - FAQs or you can find your handset on our following website to have the configuration settings for mobile internet sent to your phone: Online Send Phone Settings. If your handset isn’t on this list, you will need to manually reset the APN settings.
Also have a look at the following online Help & Support Page: Roaming Hub if you have access to WiFi.
If you are still having an issue with this, please send me a private message by clicking this link: PM me here and provide the following details:
Full name on the account
* For other forum users reading this, please only PM me if I have asked you to first.
With your phone on, please try removing the battery (if you can--if not, power the phone off for a few minutes). Reattach the battery and power the phone back up and see if you have a signal for calls and mobile data.