For car owners: parking won’t accept registration of minivan but old contract allows

Not sure if I’ll get any valid responses, but we are currently renting a parking spot from a parking lot company and we are changing from a minivan to… a minivan. But they said they no longer allowed cars of that size to be parked in their lot. And they took our initial fee with no intention of refunding.

Any legal course of action we can take to state our case?

Edit: adding to this is that we need evidence of parking in order to be able to pick up the new car and because of this we might not be able to do that and we already paid in full.