I want to change our verified mobile number from my husband's cell number to my cell number. I get an error message stating that my cell phone is associated with another account. I spoke with customer service last night, an actual person, and was told this was fixed. But it is not.
The question is whether your mobile phone number is currently tied to another account. The best way to find out is to link them. You can go here https://customer.xfinity.com/users/add-user and invite your mobile phone number, verify the account it's currently on, and remove the mobile number and add it to yours.