How would "verified refunds" be filed?

Not enough information provided. I would call the company or agency you are asking about and ask them how they file refunds if you are asking about a specific place.

There are many ways to file refunds. It could be alphabetical, by the original purchase order number, by the check number, social security number,or some other type of control number. A lot will depend on what information you have and how you want to file the paperwork so you can find it when you need it. Also if you have a large area like different states you may want to file first by Alphabetical by state name, then by another method like last name or by social security number. Or if you have different facilities you may have it first filed by facility name or facility number then by control number.

First thing to do it figure out what information you have that is unique that you can use like a control number or a case number for your filing system.