I think you have very good grounds for PCN cancellation based on your narrative, but you may have to lay it out in more detail than you have done here. What have the police provided you with ? Normally one makes a statement to the police and they give you a copy of it.
The closest statutory grounds I would think are applicable is: -
"the penalty exceeds the relevant amount in the circumstances of the case"
But wait a bit to see what others say. Don't miss any deadlines on the PCN though.
