Roaming frustration

If you eventually manage to enable international roaming (sms only) through the extremely poor call centre service, you are then unable to make calls from your phone. The only way then to disable the roaming option is by calling the call centre! How do you do that if you calling capability has been disabled iin the first place!!! The only way to do this, is to find another phone to phone from. This means that when you are on your own you are stuck! And by the way, outside office hours the call centre service is non-existent, as it seems the call centre staff are random people working from home