I contacted the Airport using their website. There didn't seem any other way to contact them. Their reply:
"Thank you for getting in contact with us. By way of introduction, my name is Edward and I am one of the Customer Feedback Team for East Midlands Airport.
VCS, also known as Excel Parking, are a third party company who enforce the "No Stopping" zone in operation in and around the airport site, issuing fines to people in contravention of this. As such, you would need to take any correspondence in appeal of your fine up with them directly. We would not be able to assist with this.
You should find the information to appeal your fine in any correspondence they have sent you, including any escalation process as necessary, or you can also visit
https://excelparkingservices.co.uk/contact/.
While we would not be able to assist further with this matter, I hope this helps point you in the right direction.
Kind regards,
Edward
Customer Feedback Team
Olympic House, Manchester Airport, M90 1QX"
I also posted this on MSE, and a couple of people have pointed out VCS are a different company to Excel Parking and I need to go back to Edward/Airport to escalate further. So I'll look into this.