SAN DIEGO -- A San Diego man found something that didn't look right on his phone bill -- and that's sparked a class action lawsuit that could involve millions.

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Sprint is accused of overcharging customers using their data wireless cards. Those cards offer broadband speed for customers using the portable cards to connect their laptops to the Internet.

Eric Taylor of Hillcrest first noticed the fees on his Sprint data card bill. When he notified Sprint, Taylor says the company acknowledged the mistake and eventually stopped billing the fees. However Taylor says he has not received a refund.

The Utility Consumers' Action Network (UCAN) has included that complaint in a class action lawsuit. According to the consumer group, Sprint improperly charged data card customers certain taxes and fees that only apply to cell phones.

"They went ahead and charged these customers state regulatory taxes as well as federal related charges that they shouldn't have been charging," says UCAN attorney Art Neill.

Other charges, such as 911 fees and FCC charges that are perfectly legitimate on your cell phone bill should not be on your data wireless card, UCAN said. Neill said some card users were getting charged for text messages -- something they can't even do on their laptops.

Kathleen Dunleavy of Sprint told NBC 7/39 they have just received the complaint and are reviewing the circumstances.