Unable to change phone number on secondary account

I want to say the reps in the store have been great, but they can't seem to fix the issue. Friday night my phone was hacked and cloned. Requiring me to get a new number. After logging into my primary account, I realized that my secondary accounts had my old number nonfunctioning number. When I try to change the number on the secondary account it tells me that the "the number is associated with another account". I have read at least 2 other posts complaining about the same thing and the attitude is "oh well that how it is deal with it." As I said in the beginning the reps in the store have been great, but they don't understand why this is this way. 

The way I see it if I have to recover that email or authenticate my log in, I have to use one of the backup emails which I may or may not have access to. This obviously seems to be a problem, but Xfinity/ Comcast doesn't care!! And I really think it's kind of stupid that even the reps don't have someone to call if they have issues that can't be fixed. And there is no support other than going to the store or here.