I had dent devils come out and do a dent in my ST 2 days ago. Obviously they're a franchise, so they're only as good as they're individual operative, but I was chatting to the guy and he said it takes them 3 months to train. He did a pretty good job on mine:

Before:



During:


After:



£75 + vat per panel.

http://www.dentdevils.co.uk/technicians.htm