Has anyone appealed a fine for not having p plates on? Was it accepted? What excuse did you use?

I somehow ended up with a an asshole officer who fined me for not having p plates on, during a rbt. I genuinely didn’t know that my p plates had fallen off, he acted all nice like ‘oh yeah it happens a lot’ and even told me it wasn’t worth me getting the permanent p plate mounts put on as it was a company car and I get my full license in a few months anyway, then proceed to give me the fine. I get it ultimately comes down to police discretion but I actually didn’t know and he didn’t seem to care at all.