Yep typical BS they sprout down here
Hence why I get mine serviced at Autotech in Rangiora...
Anyway as you said mate Ichiban stated it a few times that they just hooked it up in the service bay then retarded the timing... Disconnect battery you loose the "tune"
To do the so called tune for our fuel all you do is clear any error codes, disconnect the battery for about 15min, then reconnect and drive around nicely...
Voila...
Save your money and do the above.
My GTB had pinging issues years ago (brought on by some engine & exhaust mods), this was fixed with a poked O2 sensor replacement, & knock sensor replacement plus some good ol' Upper engine cleaner...