andrewNZ: The first thing I'd be doing is getting up and having a look myself. I don't trust those people one little bit.
If you're going to spend money, dont spend it with HRV/DVS. Positive pressure systems are a bloody scam. (I could rant for days about why)
Go with a real balanced pressure heat recovery ventilation system (one with a heat exchanger). Smart-Vent do it, as do Cleanaire.
Be aware Smart-Vent also do a cheaper positive pressure system, you don't want that.
Can you link to the exact product you recommend? What is the cost approximately?