Fair trade officers must investigate the "hidden" charges faced by holidaymakers when buying foreign currency, campaigners have said.
The watchdog Consumer Focus has made a super-complaint to the Office of Fair Trading (OFT) over the charges on spending money abroad.
It says the charges are too complex and wants to see better information given to travellers.
The group estimates that around £1 billion is spent on exchanging money every year, with a number of charges imposed on using credit or debit cards overseas.
These charges can create additional costs for holidaymakers, making it even more important to save money on other essentials such as travel insurance.
Consumer Focus also believes marketing phrases such as "0% commission" and "competitive exchange rates" could mislead customers.
It wants the OFT to investigate the charges to help customers get a better deal.
"Many of us travel abroad every year and we face a confusing array of often hidden charges every time we buy currency," said Consumer Focus chief executive Mike O'Connor.
"Converting £500 into Euros can cost from under £10 to over £30 depending on where you switch your money. This is a huge difference for essentially providing the same service and typically banks offer the worst deals."
© Press Association 2011