How to complain to executive customer service team for Mobile service overbilling?

How can I reach the executive customer service team regarding an overbilling issue.  I've called in a couple times and got a complete run around.  The overbilling resulted from Global Travel Pass $5/day charges in Mexico on Unlimited lines. According to support documentation, that $5/day in Mexico should be waived for Unlimited lines. (link) When I first called in about the extra charges, a rep (I think named EJ) assured me they could waive the ~$120 in charges across three unlimited lines, but we just had to wait for the billing cycle to close. Now that the billing cycle is closed, I called and was told they cannot be waived and the supervisor was very firm that even though he thought they should be waived, he couldn't waive them and he couldn't escalate my call further or have anyone else follow up with me. There was also a lot of discussion around 4th and 5th generation plans - new news to me and something which is not discussed on the support website that I linked, and is not visible to the customer. Had any of this information been clearly articulated, I would have a) used a local Mexican SIM chip for $20/line or b) not upgraded to unlimited for multiple lines (specifically looking to avoid the $5/day charge).  I'm also really upset with the reps for 1) providing misinformation 2) changing my plan without my consent (really upsetting - but I had the manager change it back),  3) not providing a reasonable credit given the amount of misinformation on the website and prior rep conversations.

Who can I reach to get this resolved?