Do you have any of the old gas bills, so you could fax it to the gas co., to prove you had two legitimate lines and gas meters?
Also, there are times, when all else fails, you may need to get an attorney. This maybe one of those times. The gas co. may respond better to them.
One more thing — the guy you talked with may be a supervisor, but he still has someone over him. Ask him for the name of his boss and send him a letter, registered mail.
It would be good to have that and give the info to your attorney. As I said in my previous post, you may need one in your situation.