Free Traffic Legal Advice

No, why would you?

If your account is accurate, then you were parked as stated in your appeal and FP's own records - their claim is based in 'double-dipping' - should show this. ECP's evidence was almost the equivalent of exclusion fingerprints, they would prove a negative whereas FP's can prove your case.

The BPA's Code of Practice is applicable here:

Issuing an 'overdue' notice doesn't seem like 'stopping work on processing' to me - you may wish to write to them to express your surprise in receiving an overdue payment notice when they have not yet responded to your appeal. Ask for confirmation that they have received it, and perhaps attach a copy in case they haven't.

Do you have proof of submission?

yes I had proof of receipt.

I emailed to ask why it hasnt been put on hold and received a notice today that the PCN has been cancelled.
Thank you all for the support!