Do you know the reasons as to why they get the games? Have you spoken to the appointments officer?
Being an appointments officer is a thankless and almost impossible role. They will generally try to look after people based on their requirements, but this isn’t always possible- you can only please some of the people some of the time, not all of the people all of the time; a bit like refereeing itself.
I’d be very surprised if it was in some way discrimination.
At the end of the day, no one can force you to referee a particular game/club/league. But on the flip side you can’t force yourself into a particular fixture.