Be as utterly ruthless and nasty (or mocking) as you have to be. Remember, these are organized gangs of international criminals trying to get control of your computer, downloaded viruses, and demand payment to “fix” it. Frustrating them and wasting their time is paramount. The Indian government really needs to crack down hard on these criminals and give them long prison sentences. It’s giving their country a black eye. Contrast it with Nigeria whose email bank scams are quaint by comparison (and easily deleted).
My husband plays with them. I just don’t have the time or inclination, so I let him answer the phone.