Livid at ridiculous cancellation services

I cancelled my wifi account in Feb with Telkom after some fights. I have escalated it and eventually received confirmation that the account was successfully cancelled after having paid my cancellation fees (over r2k)

I now receive an invoice from telkom for payment??!!!! Please sort this out. Your pathetic cancellation department is prejudicing many people and you are NOT entitled to debit my account or have me reflect poorly as a payer due to your inefficiencies.