My question involves landlord-tenant law in the State of: PA

hi, i had a room that racked up a 600 dollar ugi gas bill, and he has recently moved out, it got shut off. now my question is this, can ugi actually make me pay that 600 dollars and put the bill in my name, i called them and they are telling me a law was passed that says they are allowed to put the full bill in my name now.

i still talk to my old roomate, and he said that they still have collections calling him for the same bill, so 1 can they bill me, and 2 can the collect for the same bill twice like that? and three what the heck law are they talking about that was just passed?