So the DA is contractual? Are you sure? Or is it a bit like the numbers on the aircraft being contractual?
Whatever the truth of the matter is, while you are in dispute with the company no-one really cares about the DA being imposed. After all what are you going to do about this imposition? Hold a strike ballot? That is happening already and so there is no threat in that.
No court in the land will accept that during exceptional weather conditions like this that a multi-national company should have to go cap in hand to the likes of DH, who does not work for them, and ask for permission to conduct company business. The fact that it has even been brought up here shows how deluded and out of step with reality some in the BASSA camp are.