Motorhome Habitation Check

I have recently had a habitation check on my motorhome. I chose someone who is a member of the Mobile Caravan Engineers association, however, my local dealership said this is not a recognised qualification and he should belong to the National Caravan Council. The dealership said his habitation check was not compliant with NCC best practise and as such would not maintain the manufacturers' 3 year warranty. Does anyone know if this is correct?