Beware of Duty Free, especially when you have cash...

Beware of Duty Free, especially when you have cash left in local currency and you buy by topping up the card charge. Twice the same day in two different funds, while taking the cash, they "forgot" to deduct it from the amount charged on the card. After the protest they returned the 15 euros in the first case, in the second case they "forgot" to deduct 4 euros, which they did not prevent due to boarding the plane.