Originally Posted by Nationwide

For regulatory and anti-competitive reasons VISA* is unable to prevent the operation of DCC by retailers or ATM providers but has introduced rules to govern it. Prior to the transaction, a shop or restaurant offering the service should verbally inform the cardholder of the payment choice available, but language barriers will often prevent this. This should be followed by a statement on the signature slip illustrating the choice the cardholder has made ...

It has become evident that some retailers are not complying with the rules set out by VISA and are applying the conversion service automatically without the cardholder’s consent. Therefore, customers are paying in sterling at exchange and commission rates that are often unfavourable. Some cardholders do insist on paying in the local currency at the point of sale but the retailer will sometimes refuse to switch currencies ...