My experience was similar to P.A.S.'s. Caller said they were giving a 10% discount on gas to my house because it was used for "home heating". Caller knew my address and name. Asked for account number, which surprised me so I asked why he didn't have that information if he was in a position to offer a discount though Washington Gas. He just answered that he needed the account number. When I asked if info could be sent in writing, he said there was no need since phone calls are recorded (?!). Having wasted 30 sec of my life, I hung up.
The person did call back. Spoke in British Accent. He stated that he is calling from SmartOne who supplies gas to Washington Gas and because gas is being used for home heating they want to give 10% discount for two months.
I stated that I want something written and person raised his voice, he said there is no papers to sign, I will just get discount from Washington Gas and letter from them.
As soon as I said that my Dad is the account holder, he abruptly said "thank you for your time" and hung up.