Can you clarify what you mean by "moved abroad" - do you mean you are now no longer a UK resident?
I ask because EE is a UK network operator and roaming facilities are intended for users who spend short periods abroad, not those who are permanently based outside the UK.
Enabling billing add-ons doesn't, of itself, activate the roaming facility which allows your phone to connect to foreign networks. If you're not able to enable those via self-service (app or website) methods, then you will need to call EE C/S - this can often be done via a web-calling app such as Skype (using a WiFi-connection) if necessary,
