Dispute Regarding Promised $400 Promotional Credit Misrepresentation

I am writing to escalate an issue regarding Xfinity Mobile’s failure to honor a promotional agreement. I am an existing Xfinity Mobile customer with four phone numbers and a smartwatch on my account. I visited an Xfinity store with my daughter to add a new mobile line. The store manager specifically recommended a bundled promotion: if I switched my service to Xfinity from another carrier and purchased a new iPhone 17 Pro Max, I would receive a $400 promotional credit. The manager assured me that adding a fourth line to my existing three-line base plan (originally $90/month) would increase the cost by only $30, bringing the total to $120/month. He also stated that the monthly installment payment for the iPhone 17 Pro Max (512GB) would be fixed at $27.75. Additionally, he offered a free Apple Watch SE 3 (aluminum case, 40mm), with a service fee of only $10/month; I accepted this offer. Based on these specific terms, I proceeded with the switch, activated the new phone, and successfully ported over my existing number. However, my bill does not match the promised terms at all:
1. The base plan cost for four lines is billed at $130/month instead of the promised $120/month. 2. The installment payment for the iPhone 17 Pro Max (512GB) is billed at $38.88/month instead of the promised $27.75/month. 3. The promised $400 promotional credit has not been applied at all. (Note: Only the $10/month Apple Watch service fee is billed correctly.) I have attempted to resolve this issue through all available internal channels but have repeatedly faced runarounds:
• August 4: Called customer service; they offered only a small, one-time $10 credit and told me I had to return to the store to resolve the issue. • August 15: Visited the store; the manager was not present at the time. A few days later, a store representative called to state that my plan did not qualify for the $400 promotion; instead, because the original store manager had left, the new manager offered only a partial refund (or credit) of $100—an offer I could not accept.
• August 21: I called customer service again; they offered only $40 credit but failed to resolve the ongoing issue of overcharging.
• August 25: I called customer service again. The supervisor refused to resolve the issue and instead deflected responsibility, telling me to either return to the store to secure the $400 credit or contact the billing/collections department. I have spent dozens of hours communicating with various customer service representatives and absolutely refuse to suffer financial loss due to misleading sales practices. Having fulfilled my obligations under the agreement, I demand that Xfinity honor the $400 credit and the originally promised rate. Please arrange for an official company representative to contact me via private message to review my account records and resolve this billing dispute. Thank you.