The first question is what the base segment fare was for the F ticket. He is due 75% of that. Depending on how much he paid for his ticket and how much of that is base segment, it is impossible to calculate whether he is due more and, if so, how more. As to the form of payment, it is more than likely that BA will reissue that either in his preferred local currency or as a check or bank transfer as the case may be. In other words, a Yen card if he lives in Japan.

I would forget about the drip. It only detracts from the central issue here and frankly, if he did not take it up onboard, not worth much now.