Poor Administration

I cancelled my contract in June cause I'm currently unemployed can't afford montly payments, suddenly from August I'm receiving emails that my account was in arrears I called customer service they said my number its on prepaid they can't see the bill, went to Soshanguve crossing branch they told me the same thing, now I'm receiving final notice emails that if I don't pay I will be handed over pls check your administrations this is so unnecessary