Xfinity App and iPhone8

As I am not having success obtaining information about land line billing issues (after spending hours) with the Xfinity web site, online chats, and calling various phone numbers (which ultimately lead to a dead end as the choices do not apply--and there is no option to talk to a person), I am attempting to use the Xfinity app via my iPhone8 Plus IOS16.7.11 to get answers to landline billing questions for my elderly mother.

Quite some time ago I was logged in via app on phone and apparently today I was still logged in as I was able to access some information.  I eventually received a message with a red & white "!" and message "Looks like you need to update this app. This version of the Xfinity app is no longer supported. To continue you'll need to update to the latest version." followed by black & white "Update now" which takes me back to the to the app store.

1) When and how were customers notified about the Xfinity app upgrade incompatibility with iPhone8 Plus, so that we could plan for this change?

2) How can I address a land line billing issue?  I had a land line set up for my elderly mom at a low rate and suddenly the monthly bill increased by 200%.

3) My mom moved mid June & there is still a credit on her former account--I thought I was told that the credit would be transferred to the new account, but that has not happened.

4) Last weekend Xfinity techs were addressing my mom's TV problem and switched out equipment, which caused her separately billed land line to be unavailable from Sat-Tues--how can I ensure that she receives a credit as no transaction history appears to be available/accessible online. 

Please advise.