It depends, it's always worth appealing, you might be lucky, at the least it indicates you're going to challenge them and shows you acted in good faith should it get to court.
However most appeals we see here do get rejected, mainly because people generally have relatively weak grounds to appeal. Most people who have strong grounds, frustration of contract, car breakdown, medical emergency, genuine customer will often just naively appeal and depending on the private parking company have a reasonable chance of it getting cancelled.
For example getting into a detailed argument over whether the wording on the PCN is or isn't fully POFA compliant isn't going to win any appeals. Challenging the PPC regarding sufficiency of signage (with evidence) or not providing a consideration period are stronger grounds less open to interpretation. Unfortunately you are dealing with an IPC affiliated operator and the fact they've issued a PCN without a stated period of parking would suggest they see the rules as guidelines at best.