Sign in error “access not authorized”

I need this escalated. I have Xfinity Prepaid Internet and I cannot access the account. I get “Access not Authorized,” and account recovery says “This information doesn’t match our records.” This started before I changed my phone number. The Prepaid phone support line has not been able to resolve it. I need someone to locate my Prepaid account by my service address/gateway and correct the account ownership/login information so I can refill my service.