The Man from the Bank

As Dave and I sat drinking tea at Abba Camping, we were waiting for the Man from the Bank. The idea of sitting and drinking tea, while waiting for the bank employee to come and serve you at your house, is one that I approve of. It certainly rates better than going to the bank and standing in line.
The Man from the Bank wore sunglasses, and was very slick. He could change Euros cash, Euros travellers cheques, and Dollar travellers cheques. Dollars cash were currency non grata - nobody wants them.
Dave had Euros cash. 'Do you want the official rate, or the black market rate?', enquired TMFTB (The Man from the Bank). A puzzling question indeed. It crossed my mind that TMFTB was perhaps not actually from the bank.
'If you declared currency at the border, you must use the official rate', said TMFTB. 'Very Well', said Dave, and the deal was sealed. TMFTB had official slips and a stamp, so I began to think he really was from the bank.
I had Dollars Travellers Cheques. 'A lower rate for these', said TMFTB. I had checked on OANDA, and what he offered was not too bad. The deal was again sealed, and I received a large pile of tatty, ripped OUGUIYAS (Mauritanian Currency, in case you're wondering). Upon counting my OUGUIYA, I discovered that 1000 were missing (about 3 euros). 'I'm very sorry', said TMFTB, 'I made a mistake'.
Never trust a man wearing sunglasses who carries a lot of money....