That's how telkom works

Cancelled an uncapped lte contact with telkom through DSL Telecom in May 2021 and was billed for the last month on the 1st of June, cancellation reference ***A

A week into June 2021 I receive an invoice stating that will be billed again for June for a service that was cancelled in May, I called telkom cancelations and the consultant confirmed that the contact was cancelled in May and I should NOT be billed again.

This morning the charge went off as expected, I then called telkom cancellations again and was told even though the contract was cancelled in May, I'm being charged in arears for the last month again, to quote the consultant "that's how telkom works" I'd like the charge to be refunded, I didn't use the service for June because it was cancelled.