Wrongly billed then line barred

Now sitting on the phone for the past 4 hours trying resolve my issues. My line has been barred for outgoing calls (causing major inconvenience) only to find out that they are calling my account to be in arrears when they have actually billed my wrongly. The call centre is not at all helpful, I am now on my 8th operator trying to resolve the very same issue. NOW CLAIMING THE WRONGLY BILLED ITEM IS NOWHERE TO BE SEEN. AND I STILL CANNOT USE MY LINE.