<prompt> Human: I lived in an apartment in a building in Brooklyn for a year with a friend. In September 2014 I moved out into a basement apt without any official lease. About 6 months ago I got a call from a debt collection agency that they were calling about a National Grid bill saying I owed them about 670 for gas used up to October 2015.I tried getting in touch with the landlord to get a letter stating I wasnt living there at the time, but had no luck getting through to him. My roommate was the one who dealt with him and he lost his contact info in the last 2 years. The lease has also been lost in the intervening years. The broker we used was sold to another company which claims they have no record of me ever using them. The phone number on file for the official name of the company the address of the building is a disconnected number.Im not sure how I can prove that I wasnt living there at the time they claim. I told them that if theyre collecting a debt they need to prove that I was living there at the time. The response I received was, that isnt how it works. Is that actually true? How do they not need to prove I was living there?Up until now I have mostly been ignoring it, but they put a mark on my credit. Will continuing to ignore it hurt my credit at all? Id really like to have them leave me alone.  <response>: I used to work for a utility company in Iowa so the Utility Board rules may differ. They were right in saying, That isnt how it works. If you had the utilities in your name, it was your responsibility to contact the company to take them out of your name when you moved out. If you did not contact them you are liable for the bill, even if someone else was living there at the time. The reason for this is that it would be impossible for a utility company to check every address monthly to ensure the persons living there were the one being billed. Also, tons of people have utilities in their name for other people usually for credit reasons, the actual tenants probably owe the utility company money and they talk a friend or relative into putting utilities in their name; sometimes its a sublet legal or not and the original tenant is required to maintain utilities as a requirement of the lease. It is not the utility companies responsibility to act as an intermediary between the parties. Definitely get the letter of debt validation and follow the proper steps to verify the debt is real before going any further. 