Crestcutter
Do you have any witnesses, other than your son, that are willing to give evidence on hearing and seeing those people impersonating a Fisheries Officer?
It might be a bit difficult, in court, to prove what was said if a child is the only witness.
Mate, if you have solid proof that can be used against these people, contact the QB&FP to report the incident and during your conversation with them (gently) suggest that you are prepared to go to the MInister with your complaint if nothing is done.
I know that QB&FP take a dim view of idiots misrepresenting themselves as Fisheries Officers because it can reflect badly on QB&FP officers if the impersonaters are rude or behave badly.
GES