I've taken two of my dogs to Elite Paw Spa, and have been very happy with the results. They were amazing in filing down the nails on my reluctant bulldog. He threw an absolute fit and it took 2 people but the job got done. Way better than taking him to the vet and having him sedated! They also gave me some good advice on his diet. I hadn't even realized he might be allergic to his food.
I don't know the full situation on the other reviews but it seems like unrealistic expectations that could probably be resolved by having a detailed conversation before the grooming. If your dog is matted you aren't going to get the cut you want. A groomer would have to shave them down to get the rats out. The only other option is to brush them out, which is painful and cruel to the dog. I knew my cocker spaniel was matted going in and they did the best they could with him. It was my fault for waiting too long, not theirs.