The 'new' company you allude to is 'Rentokil', a recognized global leader in pest control for more than ninety years.
On the corruption bit, you may think me naive, but I really don't think there would be any graft involved in their enlistment or on-going operation. New Zealand, along with Denmark, is ranked (by 'Transparency International') right at the top of the world's least corrupt countries - so, we assume a little more trust than average.
From what I have seen of Rentokil's performance so far it would appear that they a lot more conscientious than the other existing contractor - there was (and I think, still is) something seriously astray with the operation of the latter.
At the very least, we now have a choice of whom we pay to treat it.
I also think it is fair to say that it is too easy to blame the contractor for any leaf that comes through less than 'perfect'. Over the past few years I have seen enough parcels that have completely avoided any treatment (in NZ) and they have sometimes contained leaf that an overly discerning buyer might call 'burned'. So, 'heat treatment' is not always the culprit.