I suspect that different makers have different times and even different dealers will achieve different times so it might help to give the make & model of your MoHo, the problem and the name of the dealer. I take it its something beyond the control of the dealer. If its that serious how long have you had the MoHo? Is it too late to reject?
warranty claims for the habitation are normally through your supply dealer not the manufacturer; unless the claim is so large as to need manufacturer intervention. for the chassis its treated like a normal motor vehicle,,, any main dealer backed up by manufacturer.
so your claim for habitation warranty should be dealt with by the dealer who supplied the van.
if as in my case with our last van the dealer stopped trading 6 weeks after we took delivery, then its through to the manufacturer for guidance and send you to another dealer who will then "ONLY"! do what the manufacturer pays for upfront. it took me 18 months to get a hab door sorted to stop leaking.
warranty claim for floor delamination, and one panel with damp readings, in 2 areas of 40% and50% found on 2nd habitation check, in february van is a tribute T715, dealer recieved go ahead for floor,on friday, still awaiting go ahead for,panel damp repair. DEALER had requested a return to factory, but told to carry out repair to floor,