if it were me, i would do a couple of things: 1) talk to the actual groomer who would be doing the cutting, b/c things seem to get lost in translation through several people; 2) show them the picture; and 3) tell them exactly what you said here, that i want the head and tail longer and also that i do NOT want a shave, but a puppy cut, the length of which is shown in the picture.
if they mess it up after that, well idk
good luck!! post pics!!