Bad Service

I am emailing on behalf of my husband. He is an old nashua mobile customer and is now a MTN customer. Since MTN has taken over his account he has been billed data time, which never happened with Nashua Mobile. He went into MTN to query is account. The the person that helped him said they would look into the matter and email him within 24 hrs. It has been 3 weeks and nobody has contacted him or emailed him about his account. The data charged extra is close to a R 1000.00. This is unacceptable and his account is due for upgrade will rather have him go over to vodacom. He keeps his data switched off and only uses it to Whattsapp. He does not even use his phone to browse the Internet or update his apps.