update, used both the Toyota spray and the Forte bomb.
first the Toyota, comes as an aerosol and you have to attach a nozzle with a 15 inch tube on the end, this sprays the contents out in four directions, I took the scuttle cover off the passenger side (UK) and sprayed down the air intake with the fan on mid speed. Two issues, first it can cause a foam, although it did not spray into the cabin it took a while to clear, and second the tube is in danger of catching the fan. Good as the spray gets a direct hit on the evaporator and the car does not have to be stood idling for ages.
Next up the Forte, put the fan on recirculate, mid fan speed, let off in footwell and leave with the engine and aircon running for ten mins, then clear another five. The filters have to come out which is a fiddle, no mention of that on the Toyota. Seems to do the business, the apple fresh smell is noticable outside the car to so my door seals are not as tight as they should be. Still, easy enough, then pop the filters back in (mine were only 6 months old and still like new).
Conclusion, Forte ideal for a one off hit for a specific smelly problem and the Toyota great for maintenance ie a good squirt every few months or so.
Proof will be whether the whiff returns in a few days time, all smells like fresh apples at the moment, but that should go after a few days.