Strategy and execution to unmask and attack a deep web website owner that steal bitcoins with blackmail

Hi everybody, I'd need to find the right developer/hacker in order to denounce a website masked by onion proxy servers or some deep web mask working with tor and cloudflare. They keep registration data while you experiment an order, but after a few minutes they change your password and do not ship the product paid with bitcoins. We can do in-depth in the chat but please reply to this project only if you have security and hacking/cracking skill to put me in the condition to reach the website owner with some friendly message, or, if necessary give the right data to the competent police department, with the right instructions to denounce those cheaters Also, please send me a quotation first because it is my very first time in fighting those kind of deep web criminals, thanks SO much best regards