MTN unable to resolve my barred my sim

I have a contract with mtn, one of my sim just decided to barr itself without my knowledge apparently because I dialed a code which I don't even know as my main sim is Vodacom, meaning I only use my MTN sim for calls and data. I have called the call centre 4 times and was given a code to unbar my number which was unsuccessful on all 4 counts, if MTN can't solve this then clearly there has to be another way because I can't keep paying for talk time that I can't use due to all my outgoing calls being barred.