MTN debt collector attorney harrasses me. Bad communication

MTN sents attorneys to harasse me they calling me everyday to say i should im owing mtn money which i paid on the 1st of February the whole amount and i upgraded, i told them to check with MTN. As an mtn consultant advised me, the attorneys dont listen to me and they keep calling me, i payed the whole 9000 amount early this month. Now its like i owe people and i do not pay at work, thats messed up, communicate with the attorneys yall send to us please sort this out