I work in support, users like this are unhelpable because even if you do know exactly what the issue is and how to fix it, its unlikely they will ever believe you.
They have a chip on their shoulder and should just walk away. When someone sells you something they don't really owe you much of anything. If the product doesn't do what you thought it would or worked the way it should then get a refund and use a different product. If they won't give you refund then that is an issue, but I've never heard anyone having issues with refunds.