recommended speech therapist?

My son is almost 12. He has difficulties with the letter "r" and sort of sounds like he has a thick Boston accent. "Water" sounds like "what eww" and "car" is pronounced "cah wha". For the most part, people understand him, though sometimes he's asked to repeat a word. He's always spoken like this. We've done some speech therapy at Kaiser and he's had pull-out help at BUSD since kindergarten, but it hasn't helped. We found a good speech doctor who met with him regularly for a few months and gave him homework and there was some progress. But after a few months, he refused (he's also on the autism spectrum and has issues with compliance). I want to try again -- I'm looking for a recommendation of a speech doctor or speech therapist with particular personality traits in the hopes that my son will be wooed and convinced that he wants to work on this. Do you know anyone? Are they dynamic, charming, intelligent, charismatic? That's what he wants. Are they reputable, successful, local, not too expensive? That's what I want.