I work in a dog grooming shop and I would just tell them you'd like a deshedding package if they offer one. I don't know why groomers want to shave these dogs down, some owners actually request it though!
I always offer a deshedding service for double coated breeds, if the groomer is any good you would think they took hair off but really it's just thinned out and doesn't shed as much.
It can be done at home with a few tools as well... a good deshedding rake, pretty cheap at most pet supply stories, some shampoo and really any conditioner, i usually suggest to clients to use the remo ESPREE conditioner because it's cheap and it works but most salons order something special. I leave conditioner on the dog and then take the rake to the coat and after a HV dryer to blow out any undercoat that loosens up. If done correctly it helps a ton and you have dog hair all over the place.... so best saved for a grooming salon! Then rinse really well, and brush/blow out the dog again with the dryer. The coat should feel very nice and slick and you should be able to run a comb through it without pulling out too much undercoat.
