First off, you should speak to the therapist!! This therapist does not view SM as an anxiety disorder. If she did then she would not use the word ‘manipulation’ in describing your child’s muteness. Your child will make no progress and chances are will worsen with that type of attitude. In addition, punishing, withholding privileges, bribing, tricking, are all inappropriate ways to handle SM.
The main aspect of treating SM is to remove pressure and not to dwell on the talking issue. Desensitizing your child to her school environment, especially over the summer, frequent playdates, etc. are all ways to help your child. You need to educate yourself as much as possible to SM. Read our site, go on our forums, converse with other parents, and get yourself a therapist or physician that understands SM so your child can make progress.