MTN unable to switch off roaming.

MTN has been unable to switch off my roaming service for the last week. I have tried 11 times, been to a store twice and spent more than 2 hours on the telephone. I have not been able to use my phone for the last week but they do not have a problem billing me for the service. No one in MTN seems to be competent to switch off the roaming and a ticket has now been logged that can take another 7 working days.