I am not a lawyer but Dizzy is 100% correct. It is a scam, and the biggest crime is that the government doesn't revoke the paper thin legislation that allows these companies to get away with it.
Go to Google and do 20 minutes research before contacting the company. You will find the simple option: do not appeal. Do not contact them in any way. By doing so they could claim if it got to court (it won't by the way) that simply by doing so you have indeed entered into a contract with them, on the terms stated in the alleged enforcement notice.
I have received a few of these notices over the years. I'd like to point out I'm not talking about council parking tickets because they are legally enforceable. I've not had one of those since I was a teenager! So, as I said, I've had a few of these scam notices over the years - the most recent one when I stopped at a deserted airport roundabout to drop off a passenger who was simply picking their car up (their return flight having been diverted to a different airport by fog). I was literally stationary for 10 seconds.
Anyway, I digress. Do not contact them in any way but then you have to be brave. You will get dozens (literally) of letters threatening court action. You will have a few phone calls as well. Eventually you will get letters from a "debt collection agency" who will offer you "final chances" to avoid a debt collectors visit.
Ignore the lot.
Nobody will physically arrive at your door. No court summons will drop through the letter box. Nothing will happen. It's not worth their while.
But as I say, you have to be brave and stick to your guns. The first time it can be quite intimidating, the letters never seem to stop and the penalties threatened seem daunting. But they'll dwindle away to nothing after 3 or 4 months. Note, they may have another bite 12 months down the line. Ignore that too.
The second time is still a bit nervy. Did you somehow dodge the first one, is this somehow different? It isn't different at all. Still a scam. By the third time it's a game. Nothing will happen if you drop the letter in the bin without reading past the header.... The fourth time, now you begin to have fun and start writing to them on your terms, including an invoice for every correspondence. Surprise, surprise they don't respond because, by doing so, you could claim if it got to court (it won't by the way) that by responding they have entered into a contract with you, on the terms stated in your letters.
As I said at the beginning - if you get one of these, spend 20 minutes on Google (other search engines are available). Then decide for yourself if £40 (or whatever) is a price worth paying to avoid being bullied.
Sorry for the wordy message but if 1 person reads this and better understands their options it'll be worth my time. To the others, sorry that's 2 minutes of your life you won't get back (if you've got this far). Sorry again.....
Google. 20 minutes. You know it makes sense!
RH