Australian Competition and Consumer Commission chief Rod Sims says the ACCC's new case against Visa "will be a significant court proceeding."Earlier this month, the ACCC commenced proceedings in the Federal Court against Visa over alleged contraventions of the Competition and Consumer Act in relation to dynamic currency conversion services.The ACCC alleged that Visa "misused its market power" by "deterring businesses from [the] supplying of dynamic currency conversion services in Australia and preventing businesses in Australia from supplying DCC services in competition with Visa's own currency conversion service."Sims said the ACCC will contend that Visa "misused its market power for the purposes of preventing the expansion of DCC to new merchant outlets in Australia… and preventing businesses in Australia from supplying DCC services on ATMs in competition with Visa's own currency conversion service."Sims said this "was a big investigation."Dynamic currency conversion is a service that allows a card-holder with a Visa card issued outside Australia to make a purchase at a known exchange rate, rather than having the exchange rate applied later.