Why can’t I send/receive sms. My center number is correct.

Please. I’ve been suffering for 2 months. Why can’t I receive/send sms. I’ve contacted customer care for the past two months and they keep swindling me. My message center number is correct. I’ve been to a lot of MTN offices yet no help. What can I do to clear this. I can’t access a lot of things because I’m not receiving codes. Please MTN HELP ME OUT!!!!!!!!!!!!