Passing that kind of information as Excel file is as horrible as passing it scribbled on a piece of tissue.

If someone sold my debt (which is already stinky because after that I have relationship with a party I never entered any relationship with) I'd hope that what's being sold is bit more than my name with "iou" and some numbers. If not original agreement, then at least a statement from notary that had seen my credit agreement and someone who attests at some high penalty that it was not paid yet.