Looking for a Plastic Surgeon to perform and who has performed a Closed Platysmotomy.

Unfortunate situation for the young guy. I recommend that you seek advice from a medical center that has on its staff a Board Certified PS with special training in pediatric plastic surgery. This is my best advice. 

The issue is the age! To do ThermiRase RF on the child's neck would require general anesthesia in a hospital setting. Plus it could take more than 1 operation. The $$s would be very high...

A variety of options exist for treating this condition, but ultimately may require open surgery. Botox has been used to treat platysma banding but is likely to be temporary. Steroids could help but once again side effects are known to occur. Radiofrequency ablation of the cervical motor nerves (Thermirase) has been used to deinnervate the platysma muscle. I recommend that you return to the surgeon who did his original surgery.

This is an easy question. A three year old who needs corrective surgery should be seen and worked on ONLY by a surgeon experienced with this age group and ONLY at a pediatric hospital facility that has the properly trained anestheologists and ancillary pediatricians to deal with all aspects of his care. This is an unusual problem and having experience and the proper facility backup is paramount to a good and safe result.