If you've ever looked at your credit card statement and wondered why you're getting charged fees for things you didn't intend, such as an unwanted auto-renewal or unintended subscription, you may be the victim of "grey charges," a term to describe credit or debit card charges that happen due to misleading sales or billing practices. These charge can add up as well. Personal finance protection company BillGuard estimates that American cardholders spent upwards of $14 billion on "grey charges" in 2012, and it's got a smartphone app to help consumers identify them.

BillGuard, along with research and consulting firm Aite Group, recently published a study on the economic impact of these charges. The report states that credit and debit cardholders spent $14.3 billion on grey charges in 2012 and made up nearly one-third of all card transactions. The average grey charge cost $61, and if the charges were divided up among all cardholders, each person would be on the hook for $75.

What types of charges do these include? The overwhelming majority of grey charges stem from what's call "Free-to-Paid." These charges come about when a consumer receives a product on a trial basis. That product may be free or not cost very much, but once the trial period is over, the cardholder is automatically charged if they haven't canceled or returned the product. Free-to-paid charges accounted for about half of all grey charge transactions last year, costing cardholders $53 per transaction.

Other types of grey charges that BillGuard categorizes sound monstrous. These include "phantom" and "zombie" charges. A phantom charge is one in which a cardholder gets an additional product or service with a transaction. Sometimes merchants work with third-party sellers to provide these items. Zombie charges come about when a subscription or membership doesn't end, even if the cardholder has cancelled it.

Grey charges can also occur through unintended subscriptions, misleading advertising, membership clubs that send merchandise and charge for it unless the member says otherwise, unwanted automatic renewals of annual subscriptions, unintended purchases made through receiving misleading information during a sign-up process and hidden fees.

The report also found that cardholders could save $7 billion each year if they track and monitor these charges. While consumers can do this by examining their credit card statements, BillGuard happens to make an iPhone app that can help consumers track these charges.

BillGuard's app leverages crowdsourcing to help consumers identify and deal with grey charges. App users can track their credit and debit spending by using a "smart inbox" that has an e-mail-like interface where they swipe through prioritized charges. Then all the app users work together as a community to identify questionable charges, even highly cryptic ones, and provide merchant information. If a certain charge comes up a lot as a grey charge that users dispute, it's red flagged for any other user who also turns up a similar charge.

"We have built the largest crowdsourced transaction monitoring community in the world," said BillGuard co-founder and CTO Raphael Ouzan in a statement. "As consumers ourselves we realized early on that bill checking for most people is a long arduous task that most would prefer to avoid. So we set out to develop a tool that would make bill checking fast, fun and exceptionally effective, with a little help from some very sophisticated algorithms and millions of fellow cardholders."

When a user finds a grey charge on their credit or debit card account that they want to question or dispute, they can do so directly from the app itself. The app also helps users manage account balances and recurring charges.

The free version of the BillGuard app allows users to manage two credit or debit cards. The premium version will manage 10 cards and costs $9.99. The app is available through the iTunes store.