Return or exchange without original sale?

[DailyNightly87]

Often times, customers will return to the store with something that was purchased for them as a gift and they don't have the original receipt or record of the sale - but the item will have our tags so we can confirm it was bought at our store. In true Shopify fashion where the developers of this app clearly haven't worked a day in retail in their life - there is no easy way I can see to do a manual return without having the original sale handy. At this stage, I have to calculate the amount they'd get for the item and then manually subtract it as a discount - which is a quick fix but doesn't do anything to account for inventory going in and out etc.

Has anyone managed to find a work-around for this? Or am I just missing something?