I would take a look at what they are providing. Fuel is up, food is up, other stuff is up. Their access fees to land shouldn't change, their labor costs shouldn't be 30% more, processing shouldn't cost more.
I would probably call and tell them I was surprised and ask them to explain the cost increase. If they can't or you get a generic "everything is more expensive", I would ask for a refund.
I agree, it all depends on what the contract says and how much trouble you want to go through if they don't play nice.