I have to say, having now seen your photos, that this doesn't look at all like a bay. because the kerb is raised. This indicates that all they have done is widen the footway, and used blocks rather than the,(probably), more expensive paving slabs. I see that there is a loading restriction too, as there are kerb blips.
I'm afraid it doesn't look hopeful to me based on the contravention itself; the PCN would seem to have been correctly served, but there may be a "technical" appeal argument that others may see.
The absence of a bay sign indicates the location may well be within a CPZ.