VTNZ changed their mind

I purchased a bus to convert to a motorhome. The bus had been deregistered when it was taken out of service so needed to go through compliance. I took it for a pre compliance inspection at VTNZ to get a list of anything that needed doing. They told me it required seat belts for the front seats.
I engaged a certifying engineer who advised the best thing was to purchase seats with seat belts already attached. That way I wouldn't have the expense of having to get frames made as the seats could be bolted through the chassis. I managed to get a single and a double seat from a later model bus than mine and the bolt holes were identical to what I took out of my bus. I only put the drivers seat prior to the compliance inspection.
The bus passed compliance and a COF with just the driver seat fitted so was only registered for one.
Two weeks ago it went for another COF with the passenger seat fitted as well. They failed it on the passenger seat as it needs certification. FAIR ENOUGH but, they failed it on the drivers seat as well, saying it's NOT compliant.
My question is, how is it not compliant now when six months ago and only 34 kilometres more that the previous inspection, it was fine?
I spoke with the examiner and he said it was "His Opinion". WTF?

"The examiner's Opinion", can only related to items that may need further testing by a specialist for compliance to the written regulations to prove Yes it's ok or No it's not.

Ask him for the specific regulations he used, to fail the seats this time.

this stuff you take up with higher persons as in vtnz . not the examiners .