Ignore the CAB. They are worse than useless when it comes to unregulated private parking matters.
What you have not done is explained yourself clearly. What did you go to the CAB with? Have you received a CCJ? Do you even fully understand what a CCJ is and how you can get one?
You would only be advised to pay a £313 fee if you had to apply for a set aside of an already issued CCJ. So, show us what you showed the CAB and we can advise fully.
Do not expect us to base any advice on waffle that makes no sense. Show us the images and only redact your personal information and any claim or PCN numbers. Leave ALL dates visible.
From what you have said so far, it sounds that you have possible received a judgment in default.
Is your V5C registration document up to date with your current address? One of the biggest faux pas that motorists do is update their drivers licence when they move but fail to grasp that the V5C is a separate document and needs updating separately. In the meantime their Keeper data is their old address and all communication about the PCN was never received.
So, a few questions to answer before we can move on.