Well I finally landed 6 boxes - and about to actually eat one for lunch. I was a little perturbed when a store staff member bought 6 just ahead of me.
As for the other so called super bonus on cheese strings, the ad said "28s", which do not seem to exist but the store illustration over the product showed 16s which did not trigger a bonus when purchased (subsequently adjusted and the sign removed).
I have always found major problems with Sobeys bonus products, so this whole episode is no exception.