So you also missed the yellow line separating the bay where you could pay to park, plus the sign for the bay right next to where you parked ? I get the impression you were in a hurry, correct ?
The presence of that yellow line means the bays either side of it a separate and must have separate signs, which here they do.
Frankly, I cannot see any credible appeal argument, but notwithstanding this, we always advise people to at least submit something, even if its just an appeal for leniency.
If there is a 'technical' appeal argument, I'm sure somebody will be along to tell you. Such appeals are based on council mismanagement of the enforcement process even if the contravention is made out, and can win, although you invariably have to risk the full PCN penalty to get a ruling.
