@YvieJ , if on pay monthly, did you make sure that roaming is enabled on your account? Buying a roaming add-on does not enable roaming on your account, you have to enable it.
Have you tried rebooting your phone? Also try a manual search for a network.
To contact EE customer service dial 150 from your mobile phone or ring customer service for free using Skype or another phone: +44 800 079 8586 or +44 800 956 6000.
