How do I protest a speeding ticket?

Hey guys

Looking for some advice here but a few hours ago I just got caught on the highway going around 155km in a 100km zone

The RCMP officer gave me a fat ticket and a court summons but I’m pretty his radar gun was faulty. I also suspected he might have been high AF

I really can’t afford this ticket. Does anyone know how I can fight this or get a lawyer who will be pro bono?

Thanks in advance