Thanks for your advice Johanna.
I was thinking that there's nothing that could happen to them if they broke the contract, I'm sure people do it all the time.
My only concern with another rescue in the area is that they all know each other, and PAWS, for example, may not take the dog, because they know he came from GRR, and that's where he should be returned. I'm sure we could arrange a transport if we found a suitable home or rescue, though.