What is interesting to note is that the discount is always offered again (unless there is a second template for rejecting at 100% which seems possible).
The paragraph about not paying and appealing at the same time is not legally correct. The Appeal will always be against 100% of the PCN. If you pay and file an Appeal, perhaps to be heard on the papers because you are going on a round the world cruise and so wouldn't want to miss the payment date, the Adjudicator will automatically order a refund if you win. What you can't do is make an Appeal and pay 50% in full settlement. Having your cake and eating it isn't allowed.
The unique appeal verification code isn't actually unique, it identifies a date and a type of PCN. Lots of people get sent the same code on the same day. If you lose your code you can get help to Appeal on line here. You can also start an Appeal by letter without needing a code.
Councils love to frighten motorists. When they write about an extra fee for registering the PCN as a debt at the County Court (which doesn't incidentally appear on your credit record) they are hoping you will think it is large. They are referring to the princely sum of £9. Also because of previous bad behaviour by bailiffs their fees are now set by law. £75 for notifying you they have a warrant they will enforce. £235 for any number of home visits. So, not a blank cheque to charge their 'own costs and fees'; only the fees set by law (still best avoided though).
The line 'it will then be too late to appeal further' is designed to put your off from doing anything but pay up. It is unfair. It is technically correct that if you miss a deadline you can be liable by default and that councils may disregard any representations made out of time but if something has gone wrong, such as you were in hospital or in prison for a short while, the council should give what you have to say some thought. The system is not intended to punish the innocent, although it often does.
It is a common error to write back to the council if you don't like what they say and by that means to time yourself out of an Appeal. Don't do it. Just start an Appeal as there is a one in 4 or 5 chance that the council will give up at that stage anyway.
The end.