I last used my simcard for unlimited data in September

I last used my simcard for unlimited data in September. I called rain to cancel my Sim on 31st October 2023. The lady said I owe 998. I immediately paid the 998. I called rain on the 1st November their number didn't go through. I called them 2nd of November 2023. I spoke to Asanele, who then confirmed that my Sim was cancelled on the 31st of October 2023 but I owe them an invoice for November 2023 which amounts to 499. R499 for something I didn't use and was cancelled on October 2023. I'm not paying it. I'm dissatisfied and rain is a *******.