You've left matters very late, but provided you register your appeal - and this is all you do- then you can add further representations as and when evidence is provided by the authority or discovered by you.
IMO, I suggest you go with: (but wait for others)
Contravention did not occur;
Amount paid to secure the release ......exceeded the ....circumstances of the case;
Procedural impropriety.
I think this is the authorisation:
https://assets.dft.gov.uk/trafficauths/case-3525.pdfThe sign must have 3 sides.
Check their photos, all 60+ of them. IMO, you won't see one which shows or even suggests the presence of the side arms. (even your neighbour's photo - about which I suggest you keep quiet because it's the council's evidence under scrutiny - only shows one arm, facing away from you.)
So, I suggest the following:
You are unclear as to when you parked. Now that the authority has provided the date on which the sign was erected it could have been that you parked after that time: all you know is that you saw an uncovered traffic sign, albeit 30m away, but did not see any indication of a suspension sign or anything else hanging on the post. On reviewing the authority's voluminous photographic evidence, you notice that none of these shows the suspension sign with clear side arms, there being only a single photo taken from head-on. This raises serious doubts in your mind that the sign authorised by the SoS was displayed as required which would explain why you did not see it: there was nothing to see.
Alternatively, if indeed you parked before the stated date and it's shown that the authority's records do not withstand scrutiny in this regard then the second grounds of appeal apply. You cannot be certain at this point of the validity of the authority's claim because at the date of writing their records have not been provided despite being central to their grounds for removing my vehicle to the pound i.e. their policy and clear statement in the NOR being that had my vehicle been in situ then it would simply have been moved to another location and not to the pound. From this it must follow that demanding the removal fee and storage charges was unlawful and therefore the amount paid.....charge exceed ...circumstances.
As regards procedural improprieties, the first follows from the fact that the photos which have been made available to me were also those reviewed by the authority and none of these shows compliance with the SoS's authorisation (which requires that the sign comprises three clear sides) despite their claim to the contrary. You submit that this means that when rejecting my representations on this point the authority did not give proper consideration to the facts. In addition, I would also submit that when evidence is available and particularly when production forms part of a reasonable request, their failure to produce any of the key documents upon which their rejection rests constitutes a procedural impropriety.
You can ensure continuity as regards the person in which the reps are submitted, my draft rather jumps around.