Until you live at an address not in most people's postcode database. If you're lucky, you get to enter your address in manually. If you're unlucky, you're up for a phone call or total rejection - a few times I've had to collect parcels from neighbours.
I had that experience recently; being told on the phone to a utility company "Sorry, but that address does not exist." to which I replied "I'm sure it does because I'm standing in it right now."
Rather than trying to convince them, make it into a Data Protection issue. If a company stores personal information on you, and you tell them it's wrong, then they legally have to correct it. So just tell them (in writing) that your address is X, Y, Z and if they don't change it, then they are breaking the law.
