What Arrears?????????????????????????

I had a data contract with Vodacom which I cancelled months ago due to their lack of service, this cancellation was confirmed. Fast forward to today I get a mail from Hammond Pole Attorneys to contact them urgently regarding my Vodacom account which is in arrears. I spoke to a gentleman by the name Khulekani who says Vodacom has instructed them to collect the arrears that I have and he mentioned an amount of just over R1000 which I supposedly have to pay as the account on his side is showing suspended and not cancelled. My question is if I owed Vodacom why did the consultant that confirmed my cancellation not tell me that before they can cancel I must pay whatever amount that is reflecting on their side? 2. If I owe Vodacom why am I receiving invoices with a R0.00 amount, which I am confused as to why they still send the invoices since the contract is cancelled???