Line Cancelled in 2018 but still being billed

Good Day

I contacted Telkom repeatedly asking for resolution on a dispute,

The number was sent for cancellation back in 09/04/2018 and a confirmation email was received which stated that the line was already ceased in 09/04/2018 – but we are still being billed for this number,

- Date line cancelled 09/04/2018 - Latest bill date 06/05/2020

The total of the charges for the number are R262.28 + R144.74

407.02 X 24 months = 9768.48 credit needed on our account

R9768.48 is the amount that we have been billed erroneously from 09/04/2018 to date,

I have spoken to Ncumisa Jambela on the phone regarding this and I sent through an email confirming the dispute. She has said that the account will be looked into but hasn't provided any feedback yet.