I am so sorry. The good thing is it grows back , and also a good lesson. I really believe, once you find a groomer you are happy with, you should stick with them, they develop a relationship with your baby and you and IMO, you can't put a price on your babies comfort and happiness when in the care of the groomer.
Petsmart grooming around here is horrid! I always stop by the grooming section when I am in the store and watch them through the window, and I make sure they See me watching. I am always appalled at the lack of a caring/patient and sensitive attitude when the are grooming them. There have been times I sooo wanted to run in there and yell at them, and take the doggy away. I can't believe how some can even get this job. Grrrr, makes me cringe