SMS/ SMS Centre number/ Setting+ Customer Service

<p>My phone has recently started a problem of sending smses. I called the call center 173 more than 7 times and got different answers by different agents and none of the solutions worked. Its a month now and the same problem persist. When I go to the MTN store they say I should change the message centre number!!</p> <p> </p> <p>Not everyone is on social media to not be able to send SMSes!!</p> <p> </p> <p>Please assist.,</p>