pretty sure he's trying to refund the amount they paid in USD not btc, so lets say for example 0.1btc = 60$, 1 btc = 600$, then btc went down and became 300$, instead of just refunding the 0.1 btc (which is now 30$) he wanted to refund 60$ which is now 0.2btc.
Well, in the first place he asked for 10$ IN BTC, that works both ways. Since his prices are in fiat, refunds work the same. I will not accept anything under 60$ in Crypto currency.