A few yrs ago, someone tried it with me, I said, 'neuvo cocina, electricity'. which I hope meant 'new kitchen electric'. He went away.
Obviously good enough, BigEd, cos he went away. I just feel sorry for the newcomers and holidaymakers and anyone else who isn't so streetwise. I'm sure he finds a regular supply of them, otherwise he wouldn't keep coming back!
I thought the door knocking for these people was old hat, nowadays they phone for an appointment, The same as all the main gas suppliers do, this is to make you think you are dealing with them. They give you their spiel over the phone to get an invite to check your gas fittings, (it saves them a lot of time)
Just say "no tengo el gas"
Floors him completely!