Unauthorised Debicheck

This is the acc num BA*** A week ago I received a phone call from Mobile Telephone Network calling on behalf of MTN , the agent which is don’t recall her name she was selling router to me and I told her I am fine I don’t need a router because I have fibre at home, she insisted and I repeatedly told her I don’t want it little did I know that this lady has my information which I don’t know how she got hold of my account number because the same day late I receive an sms from my bank telling me to approve a debit order and I went on to my app and declined it . The following day I contacted mtn call centre and I was advise that there is nothing that they can do I need to do an affidavit and make a copy of my ID for them to cancel it . Till today I haven’t received any communication from mtn regarding the matter . Another surprise today I received another sms from my bank to approve a debit order from the same company . I need this matter resolved because of MTN works with ****** it needs to be addressed with them.