@Arewe29
I think you need to inform your neighbour that if works go ahead without a party wall award, you will apply for an injunction. As they are not following the law, I can’t think that you won’t win - and this could cost them tens of thousands of pounds, in addition to the cost of the party wall award which they will then need.
However, if you can amicably work out a solution you would prefer this course of action. Which I think will be : asking architect to change plans ensuring everything is lawful/no boundary disputes. They may need to resubmit. And a party wall surveyor on both sides, or at the very least - photos and a signed agreement between yourselves.
And then : if they still won’t budge, a solicitors letter informing of the impending injunction. And perhaps you can get together with your neighbour too, use the same solicitor. I’d choose someone local.
If any building work starts, inform the builder of the impending injunction as there is no party wall award. No builder will want this, and I think no builder would start unless there is a party wall award.
If they do employ cowboys who ignore award/injunction : then put something very heavy/immovable on your boundary line with a clear sign not to move, and then I’d call the police for criminal damage to your property if they try. Much the same as if someone randomly started sledgehammering my front wall. But I don’t think it will get this far!!
But what I don’t understand is - have they been granted planning permission?? Or are the plans just submitted pending consent?