I feel your pain!
I ,too, learned the lesson the hard way about the groomers at PetSmart here. I took Maddie there for her first groom. It is a wonder she didn't run away from home after that.
When I went to pick her up they were rude and delivered a pup that looked NOTHING like I described.
It will grow back and this is will be just a memory in no time.
I bet he's still adorable.