They do seem to be suggesting that the notice is issued and served on the same date. Seeing as it's a postal PCN, they should allow for 2 days of service.
That is the only thing I can see and it would be for someone more expirenced than me to assit you in arguing that, if I'm right
Looking back the the posts im getting that info from, what I’m referring to is a rejection of representations - It seems like it’s all legit, unless someone can see something I’m not