How do I reach a supervisor or manager?

Xfinity Mobile has given us nothing but problems. Every single time we call, they just create more problems. From billing, to devices, to services. Most recently we purchased an iPhone 15 pro max and two watches. We called to switch a number to the new iPhone. But instead of switching the number, they created a new line. Which is the same exact problem they gave us last time and took weeks to correct. Only two create the exact same problem again after we told them not to create a new line and to just switch an existing line from an old device to the new device. After contacting them to connect one of the watches to cellular service, I was transferred to the claims department. That has absolutely nothing to do with connecting a watch to cellular services. The level of incompetence shown at Xfinity is simply unmatched and only reflects poorly on the company, its employees, and its management. 

(Update) Now I’m being told to send the old iphone in with the line still attached to it or we won’t receive the promotion. Being told that they can’t switch the line to the new phone until they receive the old phone. At this point, it seems as if they are purposely creating problems. The whole point of getting a new phone is to have it active after receiving it. But they’re telling me I have to return the old phone before they can switch the line to the new phone.