Unauthorized Charges for Mobile Line [12 month Over billing]

I am writing here for formal and final demand for an immediate and full refund regarding unauthorized charges for my mobile line, which was guaranteed to be provided free of charge as part of my home internet bundle agreement.

For the past 12 consecutive months, I have been erroneously charged for this mobile service. The total amount overbilled is approximately [Calculate total estimated refund, e.g., $42/month * 10 months = $420].

Despite the clear terms of our service agreement, the billing error persists. More critically, I have contacted your customer care department approximately 100 times over the past year regarding this exact issue. On every single occasion, I was explicitly promised that a full refund would be processed and credited to my account within 2 to 5 business days. To date, not a single refund has been issued, and these repeated promises have proven to be entirely false.

The continuous failure to correct this billing error and the systematic provision of misleading information demonstrate a serious lapse in customer service and billing integrity.

I demand the following immediate actions:

1. A full and immediate refund for all 12 months of unauthorized mobile line charges.

2. A formal written confirmation outlining the steps taken to process this refund and the exact date the credit will appear in my account.

I expect this matter to be resolved as soon as possible. If these steps are not taken promptly, I will be forced to escalate this complaint to regulatory bodies and consumer protection agencies.

Account number: [Edited: "Personal Information"]

Contact: [Edited: "Personal Information"]