The postal PCN seems to be missing these statutory grounds of appeal
1) there has been a procedural impropriety on the part of the enforcement authority;
2) the order which is alleged to have been contravened in relation to the vehicle concerned, except where it is an order to which Part 6 of Schedule 9 to the RTRA 1984 applies, is invalid;
3) the enforcement notice should not have been served because—
(i)the penalty charge has already been paid in full, or
(ii)the penalty charge has been paid, reduced by the amount of any discount set in accordance with Schedule 9 to the TMA 2004, by the applicable date as specified in paragraph 1(3) of Schedule 3 to the 2022 General Regulations.
Missing just 1 ground would make the postal PCN invalid and require the penalty to be cancelled. When appealing, only point out 1 or 2 missing grounds so that 1 or 2 grounds are kept for another time. No point letting the council know the full extent of their incompetence in one go when it can be exploited.