Originally Posted by Kremmen

There will always be a spread in a market, until there's an actual transaction. Then the buying and selling value are whatever that value is.

However, this is nothing to do with forex spread. Trading markets generally list major currency spreads of around 1-3 pips. (i.e. around .0001 to .0003) Nobody would even notice if it were that small. Visa's buy/sell rates as shown above differ by roughly .01, 100 times the usual forex market spread.

Plus, of course, in refund situations, they are controlling the transactions on both sides. You don't really think they exchange your money from one currency and then back again, do you? No, they just do nothing and skim some money off the top, before giving you back less.