I have heard of MANY horror stories from Petsmart and Petco groomers. Why pay someone to mess up your dog's hair when you can do it yourself for free?
Note: I was offered a job as a groomer when I was 17, with NO PRIOR EXPERIENCE. that should tell you right there. Hire a mobile groomer, just as much, if not less, and they are done in your own home. Less stress for the dog.
I am sorry you baby had to endure that.