OP, pl just start at ..the start!
You have posted a Parking Charge addressed to Arval.
Are you Arval?
If not, then there's nothing you should do with it because it is not yours.
Let's worry about the moronic contents later e.g. 'Notice is hereby(oh what a legal sounding term, you might even think they know their a*** from their elbow, but sadly not), given to the Hirer of vehicle; if you are a vehicle-hire company please provide us with a signed statement.blah blah; the driver of the vehicle is liable; (if the charge remains unpaid) we may send further correspondence to the registered keeper etc.
FFS, make up your minds!!
If you are not Arval, how did this come to be in your possession?