Then what you do is set up some sort of monetary charge, to verify that the person you are dealing with is real. Someone willing to pay for support is highly likely to be an actual customer, not a fraudster; and you can even have their local bank or notary to verify their identity, if you are worried about identity theft.

This is a problem that is largely solved at government scale, which is what Google is now, and there's no reason not to take advantage of existing infrastructure to do so.