Xfinity Billing Issue Not Resolved after 3 months

I switched to Xfinity Mobile in June 2026. Upon sign up, I was told that I will be getting my 1st mobile line FREE for the first 12 months and second line for $30 Mobile Select Plan per.month. Besides, I also got a new phone offer or discount that I can get a new Pixel 10A phone with a single time pay-off of $117. 

Xfinity promise or agreement to me upon sign up is that my monthly Xfinity Mobile bill for the upcoming 12 months will be $0 (for first line) + tax + $30 (for the second mobile line) + tax, which should be around $38+ (less than $40 per month). However, I received a $120 bill on the 1st month, then I called the customer service team up and they adjusted the bill for me. Then, second month bill cake up showing $83++, I have to call them up again and they adjusted the bill again for that month. They told me that they have rectify the billing issue and the bill statement moving forward should be showing $38+ per month. Now, the 3rd month bill is showing $78++ !!  So, I have to call the Xfinity customer service team again, and after transferring my call to 4 different agents, no one can help to rectify the billing issue for me. They made me end the call by telling me that they will have a supervisor to call me back by end of the day due to their hight phone call traffic. I waited until 10pm ET, but no one call me back at all. 

Any idea what can I do further to escalate this Xfinity Mobile Billing issue instead of calling the general customer service line again? Thank you so much as it is very painful experience for me to have to call Xfinity every month, staying in the phone talking to them for almost 2 hours (as they keep transferring my call to other correct agent). HELP NEEDED!!!