TVLA (the TV Licensing Authority (sic)) had to change their name to TVL because they ain't got not authority!
These are meaningless threatograms from a sausage machine, based on an unlawful presumption of guilt - you need to pay us for a TV licence unless you satisfy us that you don't, and we'll send you increasingly threatening letters until you comply. Personally, I struggle to distinguish such practices from harassment and aggressive trading practices.
General advice - just ignore them. However, if you have difficulty in ignoring meaningless threatening letters, please PM me your home address, I happen to have a bridge that you might be interested in buying for a very good price.
There is a wealth of advice on YT and the internet in general, which I would have thought would have been far easier to find than we are...