More than 176 million people own at least one credit card. And one of the big giants in the industry is now being sued for allegedly misleading its customers.
As "Early Show" Consumer Correspondent Susan Koeppen notes, "Experts say credit card companies are trying to make money any way they can. So if you don't do it already, it's time to start reading your statements, looking for hidden fees."
Koeppen said, "In a country where credit is king, it's the hidden fees, that get people charged up."
Koeppen shared the story of Jill Amundson, of Minneapolis, Minn. Amundson has been a devoted Discover card customer since 1990, but was surprised when she discovered charges for a payment protection plan she never signed up for.
Amundson said, "I was looking at my Discover bill and happened to see a charge that I haven't ever noticed before."
Two years ago, company telemarketers called her at home to offer financial services for a fee. She declined, and in a phone call obtained by CBS News, she doublechecks she won't be billed.
Amundson says in the call, "I want to verify that I'll fill out paperwork if I want to enroll? You don't automatically enroll me?"
A Discover representative replies, "We just want you to review some of the benefits in the privacy of your own home so you can make final decisions there."
But she was enrolled, and it took her six months before she noticed $180 in charges.
Amundson said, "They took what I had said as enrollment, even though I blatantly said, 'You are not going to auto-enroll me.'"
But now, Minnesota Attorney General Lori Swanson is taking action. Earlier this month, Swanson filed suit, demanding Discover Card stop misleading consumers and refund fees to customers who were sold unwanted identity theft protection, wallet protection, payment protection and credit score protection.
Swanson said, "Discover played 'Gotcha!' with consumers instead of playing fair."
She added, "If they're going to sell these optional financial products, they should do so through a square deal. Do it fairly, not through fraud."
One out of every four households has a Discover credit card. The company earned more than $300 million last year from selling protective financial products -- up 37 percent since 2007.
Adam Levin, chairman and co-founder of Credit.com told CBS News, "All of the financial services institutions are looking for extremely creative ways to increase fees. We're in the midst of a fee frenzy."
Discover is also facing a class-action lawsuit accusing the credit card giant of selling unwanted services to consumers across the country and bilking them, in some cases, out of thousands of dollars.
Amundson says from now on she's reading her bill more carefully.
"I think a lot of people are like myself," she said. "You get the bill you kinda look, at the total amount, sometimes you scan it, but you might not look at it line item by line item and I think you really need to make sure you're not missing anything."
Koeppen added Amundson was given a full refund by Discover after she complained. In a statement to CBS News, Discover says they don't comment on pending litigation but they "take any customer complaint seriously" and have "worked with millions of Americans for 25 years to maintain the highest levels of customer satisfaction and loyalty in our industry"
So how can consumers protect themselves?
Koeppen advised credit card users to read your credit card statements very carefully -- line by line -- and feel free to dispute it.
She said, "Be careful with the words you choose. If you say 'OK, I'll think about it,' the person on the other line might hear 'OK' and think you have said 'Yes, sign me up.'"
She said, "No affirmative statements."