I assume that the PCN is from a company like Parking Eye.
If so follow the process and appeal. Your appeal should state something like the contract for parking is between Parking Eye and the driver. You are the registered owner but was not the driver on that day. You could also add that if they want you to check your records it will cost £100 reduced to £60 if paid within 14days. There was also no material loss for the Service Station for you overstaying by 40 mins.
They'll likely withdraw the PCN but if not then request a POPLA reference number and go through their appeals process. You'll find templates to use on pepipoo forums.