Hiya
I trim Scooby myself and like to keep him quite long, although it is a pain in this weather. I use thinning scissors, a coat king and I have just bought some really good clippers to do his head as it was a bit of a pain with the thinning scissors.
However, I do, occasionally, take him to a groomers (he's actually going tomorrow as I haven't had time to spend on his with the pup being here and he's looking a bit untidy).
First I explain exactly what I want, ie. the clippers have not to go near his body (only his head), I don't let them cut off his eyelashes and whiskers, I have his back done with the coat king and his legs etc., tidied up with thinning scissors. I even wrote instructions down last time cause I was that nervous of them using clippers on his coat.
The lady I am taking him to tomorrow has only ever clipped cockers so I'm a bit worried she doesn't know what she's doing but she has assured me that she'll just tidy up his legs and not go near his coat with the clippers
Just specify exactly what you want and write down instructions of what you don't and that way mistakes can't be made, hopefully
Or even take in pictures if you can.
