Having been in a similar situation recently with a bust iRVR machine in cat 2 we ended up diverting. Our ops manual said we could make an approach bloke on the ground said his ops manual said we couldn't.
Burning round the hold at 3000' is not the place to get into an argument so we hung on as long as we could to see if they could fix it and then nobbed off to our alternate.
Company were fully supportive which was nice.
Despite some discrete enquires I never did get to the bottom of who's books have primacy and would probably do the same again rather that face a lengthy chat with the CAA.