Unsolicited SMS messages from MTN

For the past 6 months MTN has been sending me sms messages regarding someone elses account , whose email is phuti***********@gmail.com , with MTN account number BA ******************070 (stars are to protect privacy) , however I have bought it to MTN's attention both in store and phoning their call centre, however to date, MTN has been incapable to resolve the issue, expecting me to visit a MTN store again, to report the issue, although I spent almost 20 minutes or more on my last call to MTN and being placed on hold 3 or 4 times.

Can someone that has the ability to resolve the issue , be in urgent contact with me?