how do I change my xfinity moblie phone number

I get so many spam robo-calls that my number is practically unusable. I have enable the spam blocker function, and also the don't answer unless the number is in my contacts list function, but I still have to wait for the spam calls to ring through and I end up with dozens of notifications that I don't want. Is there a way to stop the notifications? Barring that how can I just change my number to avoid the whole mess? Impossible to get anyone on the phone and talk through the issue. The chatbot just repeats junk that isn't helpful and tells me to try solutions that are not related to my problem. Really annoying how it says "You are a DIamond Customer" [Edited: "Language"] anyway. Really am tempted to go back to ATT.