Contract Cancelation

My Telkom contract ended the end of August, however Telkom still went ahead and debited me a R 100 the end of September i disputed that debit order and went to the store to cancel the contract i was then advised i was supposed to cancel before disputing the debit order, i then decided to pay the R 100 and called the cancelation department to cancel.. The lady i spoke to advised me they don't cancel contracts telephonicaly and walked me through on their website to cancel.. The cancelation was done , today im receiving an sms stating my account is in arrears with over R 400 even though i don't have an account with Telkom and i don't owe them S*** i don't know what to do anymore to get out of this fully paid contract