You could reply with the following;
PCN Number - xxxxxxx
To whom it may concern,
I am the Registered Keeper of the vehicle in question - the driver is not known to you.
Your Notice to Keeper is not PoFA compliant and, as such, there is no keeper liability in this matter.
Your options moving forward appear to be;
Cancel the PCN
OR
Waste further time, resources and money by providing me with the POPLA details.
Many thanks,
xxxxxxxx xxxxxxxxx
