Saying swipe fees for credit cards in the U.S. are seven times higher than those in Europe, more than 1,600 merchants have reportedly signed a letter urging members of Congress to vote for a bill that would boost competition among credit card networks. The letter — which was organized by the Merchants Payments Coalition — was addressed to all members of Congress, and the retailers that signed it include Walmart and Target, The Wall Street Journal reported Wednesday (Sept. 14).