Impossible to cancel after 24 month contract is over

I emailed *** on 29th July 2020 and on the 3rd August 2020 to request cancelation of my vodacom acc. My 24 month contract has come to an end and my contract is now running month to month.

Zero reply or response. When I call the call centre, the call is constantly dropped and no one calls me back.

Please cancel this contract with immediate effect and convert my number to prepaid.