Nedbank
Foreign Exchange charges

I renewed my subscription to Time Magazine SOUTH AFRICA, paid for it with my Nedbank Master Card, now i find out that I am being charged a Foreign Exchange Fee. I am told by Nedbank staff that this was a foreign exchange payment, Wish someone would explain how this is possible, considering payment was made in Rands as confirmed by Time Magazine as well as my bank statement. Staff at Nedbank tell me Master Card made the charges, but they cannot explain why - no one in the Foreign Exchange department can explain this to me