Worse experience ever

I have attempted to change my wifi passpord and user name only to find out my neighbors router has the exact same user name and password on the router and the incorrect wifi details were updated,

Problem is now i cannot change my login details

Why is it that routers with the same IP address have the same user name and password

Its also 2 different service providers

please phone me with a resolution as he is now a user name and password created by me

and uls call center does not even answer calls