I make this collateral challenge as follows:
The PCN is missing mandatory information as provided at Para. 4 (8 ) (v) of
(v)that, if the penalty charge is not paid before the end of the 28 day period, an increased charge may be payable.
Clearly, this refers to Para. 4 (8 ) (iii):
(iii)that the penalty charge must be paid before the end of the period of 28 days beginning with the date of the notice;
Therefore, it follows that the statement: "If you fail to pay the Penalty Charge or make representations before the end of a period of 28 days beginning with the date of service of this notice an increased charge of £240 may be payable” adds to the lack of clarity by its omission. Even on its own, whether the required information was included or not, it is also arguable that it conflates the two periods using the word "or" which many would view as being conjunctive. Furthermore, even if the statement were to be interpreted disjunctively, there is still no clarity due to the missing information. So, it follows that it cannot possibly be interpreted dysjunctively.
In addition, there is yet another phrase in parenthesis, which in its context, refers to date of service which exacerbates the lack of clarity further.
Finally, your website has been found to be unfair as in case Nos (First two - do not cite the whole cases):
In light of the above, please cancel the PCN.
You can select various phrases though.