With all due respect, thats a night and day situation right there. Lets be honest, you were lazy with regards to paying promptly, got caught out and then tried to argue the fact that you did pay, but late.
A proper POPLA appeal would cover at least 7 different factors at a bare minimum, so I can almost guarantee you would have got away with it if you had put the work in, but unfortunately it looks like you focused on the single and unfortunately, most damning point of all. That you didn't follow the signage.
There are literally thousands of posters on the MSE forums that have all had their appeals accepted by POPLA and honestly, very few that are rejected, IF, they followed all the guides properly.
As for the OP - I'm damn tempted to "visit" that hotel myself, just so that I can get a ticket and then open up a whole world of hurt on them. This whole situation is rediculous.
The buck should really stop at Tesla though, as their nav took you there in the first place. Unfortunately we all know the chances of actually reaching them about the issue are slim to none.