Cancellation nightmare

I am writing to express my deep dissatisfaction with the billing and service cancellation process of MTN. I returned the device on the 28th of November 2023 and cancelled the service on the same day. Despite not using MTN for the past two months, I have been billed for the service. My understanding of a month-to-month deal is that I should only be billed when I am using the service. Furthermore, the router is no longer in my possession, so I am perplexed as to why I am being billed for something I am not connected to. I seek clarification on the following points: Why is my account in arrears when I returned the device and cancelled the service on the same day? How am I being billed for a service I have not been using for the past two months? What steps can I take to resolve this issue and ensure that I am not charged for services I am not using? I urge MTN to review its billing and cancellation processes to ensure fairness and transparency for its customers. I look forward to a prompt and satisfactory resolution to this matter.