(MONEY Magazine) – Credit-card companies are imposing late fees at an ever-increasing pace. "There is enormous competitive pressure on credit-card interest rates and annual fees, and this has given way to a fee frenzy," says Robert McKinley, CEO of CardWeb.com.

SURGING RATES. More than 58% of credit-card customers say they've been slapped with a late charge in the past 12 months, according to a study conducted by CardWeb. The average late fee rose more than 5% in the past year to $29.84 and more than doubled since 1996.

SPEND MORE, PAY MORE. The latest gambit: hitting consumers who have larger balances with heftier fees. Discover assesses $35 on balances of $1,000 or more, compared with $15 to $25 for smaller balances.

TURNING PROFITS. Since a 1996 U.S. Supreme Court ruling allowed banks to charge larger penalties, late fees have climbed from $1.7 billion to $7.3 billion a year. In that time, total fees grew from 18% of card company revenue to 31%. --Christopher Windham