Rain claiming that I owe them for a service used after I have cancelled the subscription and they collected they’re router

I started receiving messages on my phone for an alleged debt of R2116 I owe rain for services consumed four months after I have cancelled my contract and the router was collected in September 2022. The alleged amount I am owing is for services I consumed to in December 2022, January 2023, and February 2023 and April 2023 even though the router was collected in September 2022. 1. I was there customer, and I gave a notice of my cancellation and the personnel from RAM Couriers came to collect the router from me in September 2022. All the monies I was owing to rain was settled before the router was collected. 2. In addition to speaking to the agents from NuDebt contracted debt collection agency, I phoned rain support and spoke to a gentleman on the 31st July 2024, who promised that he has escalated the matter to the account and logistic departments and that he will revert back to me before end of business on the 1st August 2024. He did not revert back to me to give feedback form the accounts / logistics department. I then phoned again on the 01st August 2024 to follow up on the feedback and I was again given reference number. 3. While I am waiting for the feedback from rain logistics and accounts departments, I am receiving threatening messages regarding the outstanding debt. I am very disappointed in this.