Legal action threats

I keep receiving emails from a collections company that says I owe computech R1400, sometime last month i called after i received one of these emails and i spoke to a lady who said her name was Ayanda Mbatha whom i told that in April computech debited R350 from my account, less than 28 days later they debited R129. The lady then said she can see the debit orders and she went and spoke to someone after some few minutes she came back and said my account has been closed. I then called again after some few days and another lady confirmed that the account was closed and that it will take a few days to receive confirmation. Today I receive an email I call again and spoke to another lady who then tells me that there is no Ayanda person working with her and that the information I received was wrong. I just want to know if there is any way to find any truth from these people?