My friend is a groomer for a Petsmart near Joliet Illnois. They get dogs in all the time with matts. Many times the dog owner wants the matts brushed out instead of cut out. She told me the dog will cry and scream in pain and then she wants to cry right with them. It's best to have them cut out, the fur will grow back.
As far as a place to take her most Petsmart, Petco and other pet shops have groomers as do many Veterinarian offices. Just call and make an appointment, explain that she has bad matts, so they allow for enough time. She will get a bath and all groomed and her nails done and be a pretty girl again.