I had one show up asking if I lived there. Well now. If you know who lives there you'd already have their name and be asking for the person by name. If someone were looking for me they'd know me by sight at least and know that I lived there. So anyone asking if I live there is some fucking chancer looking to extract information from me. Get wise OP and just don't answer questions from random strangers.
I just asked who they were, out of curiosity. TV licensing. Told them there's no TVs here. Shut the door. They haven't been back since. I imagine the letters will start up again at some point.
I haven't told them with a phone call or form that I don't need a license because why should I waste my time doing that? Why should I give them my name so that they can send personalised threatening letters, instead of "to the occupier", which will undoubtedly make me feel worse when I read them? A few people I've known have told them they don't need a license and they just ignored it and started up with the letters again three months later, so I figured telling them is a waste of time anyway.
OP the TV licensing people who door-knock have no rights to come into your home to check, just say No. They're not going to bother prosecuting you when they've got no evidence, it would be very expensive for them to prosecute everyone without a license and lose because they don't need a license. If you're not watching live TV or iPlayer and don't have a TV, then they can't have any evidence you're watching it can they, it isn't possible for them to have evidence of something that isn't happening.
It's an offense to watch TV without a license. It's not an offense to not tell them you don't need a license.
They can't get a warrant for your arrest without grounds for doing so. If they've caught you watching live TV by looking through your windows, then you're in trouble. Otherwise if you've done nothing wrong then forget about it.
They make out they've got x-ray vision and can see what everyone is upto at all times. They can't, they're not God! It's intimidation tactics, like everything else they do. They don't come on the date in their letters either. It says on there "Are you home at X day? We'll come then or any other day of our choice", it's not even an appointment! They're just trying to scare you into paying for a license.
If they're taking someone to court they'll need the person's name. Even if they get your name off the electoral roll (in future ensure you tick the box to make it private, so all and sundry can't see who lives there), so what? If their "evidence" is letters from Sky, those letters aren't in your name and that person doesn't live at your address. So they have no evidence then. They'll lose their case. The sodding letters aren't even about a currently running Sky contract, they're about a debt. Just make sure you show up to court if your name is on the summons otherwise they'll win by default.
Write (don't phone, as you've found out it's a waste of time) to Sky and any other firms sending debt letters. There will be an address somewhere on the letter. Tell them the person they're looking for "Mr X" no longer lives at the address since "Y date" when you moved in. Tell them you don't know this person, don't know where they live, don't have any contact details for them and that this debt is nothing to do with you. Tell them to not write to your address about this debt again. It'll cost you a bit in stamps and time, but majority of them will permanently fuck off if you do this.
If "bailiffs" turn up (they usually aren't, they're just debt collectors) it's unlikely they have any power. They certainly can't take anything of yours regardless, because you are not the debtor.
Don't get into conversation with them beyond that. Some unscrupulous ones will try to get you to pay, they just want money and they don't care who from. Don't pay them anything just to make them go away. Paying towards a debt can sometimes be seen as you taking responsibility for it.
I know you get parcels but if you open the door and can't see a parcel, don't listen to whatever they're saying just interrupt them to ask if they have a parcel to deliver, if the answer is no then shut the door.