I go to this petsmart all of the time, and have had nothing but good experiences. The groomers there are very knowledgeable about their craft. They only have the dogs best intentions at heart.
Lucky for me, I don't have a dog that will knot up if not properly brushed and combed daily. She does however not like having her feet touched. Since going there regularly to have her nails trimmed, she has become much more comfortable with the procedure, because those girls have taken the time to work with her, and I am beyond grateful.
Working to get the mats out doesn't mean getting the mats out. There's a point that you have to realize that it is in the dogs best interest to just shave them and start over. It's absolutely ridiculous and very selfish to expect a skilled groomer to put your dog in pain just because YOU don't like the idea of a dog with shaved legs, and are worried about what other people will think. It's called Humanity before Vanity, and it's something that more people should practice.
Even tonight, I watched a very skilled young lady slowly and meticulously shave a matted shih tzu, and watched it come off in one pelt. I couldn't imagine allowing a poor animal to get into that condition. The dog was so sweet, and his groomer was very patient, as it looked like he did not like having his feet touched. Granted yes, he was a naked little dog in the end, but there would have been no reason to painfully remove those mats simply because the owner would have wanted it. It's not the dogs fault that the hair got knotted up, it was the owners for not taking care of them.
It does sound to me that you are simply upset because you were told something you did not want to hear, and I highly suggest you reevaluate yourself and how you view others. They care about the well being of your animal.
And $46 is nothing for a grooming for a lhasa. My sister owns one down south, and gladly pays $60. These dog require alot of work, and a groomer should be paid for her time and skill.