OP, were you the registered keeper on the date of the contravention and are your DVLA details the same and current?
As regards the contravention:
In any formal reps pl forget all about parking bays and timings, not only aren't they relevant, they're confusing you and by the looks of the authority's rejection them as well and IMO undermining the credibility of your main argument which is that you were not parked in the vicinity of an applicable sign neither had you passed the alternative i.e. CPZ entry signs which is what I gather is your argument and not that you had, you'd noted the CPZ times but then were confused by parking place signage because this isn't a statutory defence and only goes to mitigation.
The issue is: were you parked on a waiting restriction whose times had been conveyed to you clearly and which were adequate in the circumstances?
Facts:
You were parked on a SYL which means a part-time waiting restriction.
There weren't any stand-alone upright traffic signs of the form prescribed in Schedule 4 to the Traffic Signs etc. Regs in the vicinity.
The burden then falls to the council to prove that the restriction fell within a Controlled Parking Zone whose timings were adequately signed at your point of entry into the zone by traffic signs of the form prescribed in Part 2 of Schedule 5 to the Regs with a traffic order underpinning the restriction.
In short, as regards the contravention stick to the issues of parked, there weren't any applicable traffic signs in the vicinity and as you had not passed any CPZ entry signs the restriction, whatever it was, had not been signed correctly or adequately, was of no effect and therefore a contravention could not be committed in the unique circumstances of your case.
As regards their response:
Errors/inconsistencies/incoherence/improprieties etc. don't really count for much at this stage. Furthermore, I could not see an adjudicator attaching much weight to their nonsense regarding instant PCNs given that you've not claimed that any possible exemption applies in your case e.g. loading, alighting etc.
