If only all photos were as clear!
OP, on the one hand and objectively we have two prominent, clear, compliant (with the underlying prohibition as far as we know) and prescribed traffic signs with personal observation regarding the presence of advance warning signs on all approaches.
On the other the driver was 'following Waze blindly' and a video showing, at best, that the sign on the offside might have been obscured but on the nearside totally unobstructed.
It's always worthwhile submitting reps providing that the discount is re-offered because you might elicit a procedural flaw which would support what's known as a 'collateral' challenge(there are no statutory grounds of 'procedural impropriety'). If the driver didn't see the signs, then say so and try and explain in a way which would support a 'terribly sorry, clean PCN record, will be more diligent in the future' argument.
IMO, set your expectations at a reasonable level.
Post a draft and wait for views of others regarding procedural issues.