Main contract sim not receiving sms's

I've had an issue with MTN since last year. I've contacted MTN customer service and also the Mtn store in my town. Every time the same thing. My problem was and still is that my main contract number does not receive sms's. Call centre advise me to dial loads of numbers into my fone because there are "active barring's" on my device . Each time same thing. Still does not work. When I contacted the customer complain office via email, they also give me numbers to punch in my fone. Still nothing and not one person from mtn can tell me what the problem is or how to solve it. I had to use another mtn number because my main number is useless!