Has anyone use Mark Power's Stuttering Therapy in Newport Beach? Would love some feedback!

Has anyone use Mark Power's Stuttering Therapy in Newport Beach? Would love some feedback! i am very interested in using his 2 week intensive therapy that he claims will give me immediate results. However, his $5k to $7k price tag is astronomical. I cannot seem to find any authentic reviews to help provide some assurance before handing him my hard earned money. im not trying to be cheap because if is legit, then he deserves every penny! Any feedback you guys can provide will help.