LETTER OF DEMAND/SUMMONS

I have phoned them to find out what I can do to stop this serviced, the lady on the phone emailed me what I need to pay and assumed that I will pay, as I left it to rather keep paying my debit order of R100 in December 2017 I received an emailed that I will get summoned if I dont pay R407 in 24 hours, as I emailed back explaining that I am not aware of this issue I received a 2nd email that I need to pay R508 24hours also an sms, I paid the amount in full as I was sick of this. Emailed proof of payment. Today I have received an email again that I will be Blacklisted if I dont pay, again sended proof of payment through. Please help me what can I do to get this people off my bac****