this, when i had my shop mount my EP pros i had a piece of papertape with a line saying, MOUNT HERE and my BSL written besides it + i stayed and watched
And when i had to have my bindings remounted after ripping out i didn't even trust the shop, i just asked for 4 helicoils and the tool to mount them, then i did it myself back in their shop...
just insist on staying and watching them do it, its only gonna be 30 min. max and you'll be sure they do it right....
+ its a great moment to talk with the shoptech and exchange knowledge and gnarly skiing stories ....
and if you really can't stay, label the crap out of them, indicate mounting line, the middle of the ski, indicate front and rear (some techs think twins are always symmetrical), etc...
and if they didn't fill the holes, complain, or fill em up yourself ...