Default Tenant GAS Bill Balance vs Service to Owner VA, PW County

[Neil G.]

Default tenant that owes several months back rent has finally moved out and my mom who is the new new owner (brother died and left house and assumable mortgage to her in his will) is trying to get gas service but the gas company says service is still active and past due balance under tenant's name.

What is the best resolution?

(City of Manassas, County of Prince William)