Well, putting myself in the Contractor's position it would substantially help if they had informed you of how exactly you were in default / substantially failing to comply with your obligations, as you could then attempt to correct it within 4 weeks.
So it helps you that they have not !
I think in reality it might depend on what other correspondence was in existence / circulating at the time so that an independent arbiter could assess whether it was reasonably obvious to you or not what the default was.
If it was not, then it would be termination for any other reason which allows you to charge for A2 & A4 and not have A3 deducted.
If they fail to make an assessment within the 14 weeks of the subcontract, then you should make an application which, if they fail to respond to that, leads onto another question.
So it helps you that they have not !
I think in reality it might depend on what other correspondence was in existence / circulating at the time so that an independent arbiter could assess whether it was reasonably obvious to you or not what the default was.
If it was not, then it would be termination for any other reason which allows you to charge for A2 & A4 and not have A3 deducted.
If they fail to make an assessment within the 14 weeks of the subcontract, then you should make an application which, if they fail to respond to that, leads onto another question.