There actually is a program that allows repair people to "fix" your computer clearly this is a scam and you can expect to lose all of your information to them with possible identity theft etc.
You could have told them you were with the Internet crimes division of the Los Angeles (or Mumbai) police and that he is under investigation. Why feel harassed (have fun!)
Engaging the scammers is not a good/intelligent idea-at the very least you'll just get more calls. May I ask why are you replying to a post that's 1.5 years old?
More recent viewers read them (I do, as apparently do you). Also I try to avoid answering these calls, but sometimes they have a local area code for me (spoofing?) and there is no way to tell whether it is legitimate or not. As to engaging them...if it looks odd I do not answer. It is also an intellectual/inventive challenge when one gets through. I think this is your second response to me. I appreciate the advice.