I agree that all MVHR manufacturers should make spares available. In the scheme of things, I would hope / expect that a unit would last an absolute minimum of 10 years. After that point, perhaps it is worth replacing with newer technology which is more efficient. Over the lifetime of the unit, it would be covered by a period of warranty, followed by full spares availability.
I would go further and insist that all manufacturers publish the spare parts list with prices. In the case of my Brookvent Aircycle 3.1, the fan replacements are available and a fair price. This isn't published though. With my (now dismantled) Domus HRX2D, the fan unit is available, but an extortionate price, and on top of that it is not simple to replace.
It is still early days for MVHR. The general public don't know anything about it and I expect the bulk of demand for units is from volume house builders. There is obviously little demand for spare parts at the moment and there is no secondary / copy replacement parts market. Give it another ten years and things will change as the housing stock with it installed significantly increases.
I am not sure what you are getting at here. Brook Vent Holdings Limited (NI057022) owns Brook Design Hardware Limited, Brook Plastics And Engineering Limited and Brook Vent Manufacturing Limited. In terms of ratings, the holding company is most relevant and Brook Vent Holdings Limited has an excellent rating and very low risk according to Experian. If you mean Brook Vent Manufacturing Limited, it has recently been brought out of dormancy.
My company would certainly trade with them (on good terms).