I appealed but they denied my appeal and I had to pay. Someone else posted to me that they appealed and just had a stern e-mail back and didn't have to pay. I did ask them to share the e-mail but I didn't hear back (mind you I don't find this site the easiest to navigate so could be me !!)
I didn't receive any official response on this site so waited until the date before the price would have increased and raised the appeal
On that grounds, I would always recommend appealing, as this stops the clock, and they do take a while to respond so you've nothing to lose really. You'll either be lucky or at least delay the payment process.
I hope your lucky