I don't know if legal representation is all that necessary, but that's up to you.
I believe 159 (1)(b) sits together with the "move over" laws. 3 demerit points for those. The high fine is due to increased public frustration within the last couple years for drivers who are oblivious to emergency vehicles.
As per the officers notes...
The officer activated lights and siren.
Vehicle continues. (1)
Officer activates air horn on top of that. Air horn is not his sirens. It's louder and more irritating.
Vehicle continues. (2)
Officer activates air horn again.
Vehicle continues (3)
Officer never turns off emergency lights and sirens.
Vehicle eventually stops.
Officer gets out of vehicle.
Vehicle continues (4)
Officer finally forces stop with his own vehicle.
Female driver plus two occupants. Expired sticker attached (November) and driver is carrying a G2, which of course is bound by certain conditions. I assume since you haven't mentioned it that the passenger restrictions were not an issue during this stop.
Here's the good news. It's 3 points and you avoid a 30 day suspension.
The bad news. You don't really have a defense here from what I can see so far. There is very little sympathy for those who ignore emergency vehicles and continue as if nothing is happening. I'm not sure why it's relevant that it's extremely cold. 45 seconds is an eternity for a vehicle to stop for an emergency vehicle.
There is little to no defense. Anything other than immediately pulling over and coming to a stop, regardless if the officer is pulling you over or trying to pass, is unacceptable.