Harassment by Telkom

We have had a Telkom Business account for years. Due to the Pandemic we had to close the business by end of March 2020. We have cancelled the telkom account to the end of May 2020 as we did not see any future prospects anymore. Telkom since then has refused to accept the cancellation. They claim it was not properly cancelled on technical legalities. They have sent monthly invoices for the months of June until now even after they stopped the service by end of June. They call almost every day or have some service provider call. The calls serve no purpose only harass me on my personal cell phone which is not even related to the business. They threaten with legal action and lawyers every time, but make no effort to actually resolve the issues.