Unauthorized debit order and also affecting my credit score

I had in June closed up my account and confirmed by one of the consultants.I then received a call in July where they wanted to offer me a new pakage and i said i am not interested.When i checked my bank statements un August 2022 i see an unauthorised debit order of R79 going off my account.I did read other reviews and seems like they are doing it with other people as well.On the previous contract when i pulled my transunion report they reported i missed one instalment.I checked my account and phoned them where they confirmed i did not missed a debit order and will update my credit profile.I am very upset because i have a clean credit record and they affected my credit score.