Cancelation of contract that is stil continuing

I had my I'm only cancelation in March Sim was not active since February I made payments and closed the account send the proof of pay to Business mobile and they rep**** to say my account is now discontinued and I also made a follow up to The Glen mall which I was assisted my a gentleman and the manager at the telkom glen whom also confirmed that my contract has been canceled, but I keep receiving the statement for two months now to say I must pay and now I'm in areas which last month I made a follow up with their consultant n may and now payment that was due said to be 209 May which told me he sees the matter and he wil escalated it further and I never got a response since then, today 06 June I received a statement saying I need to pay 400 and I'm in areas when I make a follow up now speaking to a consultant she just hang up the phone.