SAN FRANCSICO (CBS SF) — It’s not unusual for people to complain about their cell phone bill, but there has been a recent spike in complaints from Verizon customers over data charges.

Like many, one San Francisco woman’s Verizon data charges recently skyrocketed.

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“I couldn’t believe a bill could be that high,” the woman said. “I went to the store three times to find out why.”

But her $850 bill nothing compared to a Florida woman’s over $9,000 bill featured in one of a series of recent reports in Cleveland’s The Plain Dealer.

The person was accused of an enormous amount of data. More data than most people can imagine using a month.

CNET Executive Editor Roger Cheng told KPIX 5 data overage horror stories aren’t necessarily unique.

“The person was accused of an ungodly amount if data; more data than you can use a month,” said Cheng. “There is definitely a precedent for Verizon, and other carriers really, charging these kinds of overage fees.”

But the recent spike in data overages appears more widespread.

The Cleveland paper has reportedly received thousands of complaints from across the country. Most are from Verizon customers, but some are from AT&T and T-Mobile customers as well.

Public information shows a significant spike in cell phone billing complaints to the FCC this week, though the data includes all carriers, not just Verizon.

The FCC told KPIX 5, “We are aware of consumer complaints to the FCC on this issue. We decline to comment on whether or not we would investigate this matter.”

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It is still unclear what’s causing the overages.

Late last year, KPIX 5 reported on a similar spike in some bills due to an automatic upgrade on Apple’s new operating system.

Apple’s Wi-Fi assist automatically switched to cellular data when the available Wi-Fi signal is weak.

Many, complained they began unknowingly gobbling up data, resulting in huge bills from AT&T.

So far, it seems unlikely that feature is contributing to the recent spike in Verizon overages, since it has been around since last year.

Many complain their bills spiked without any changes to how they use their phones.

There are other possible culprits, including so-called vampire apps that run in the background, using data around the clock. Any sort of streaming video – either uploading or downloading including Facebook live and Periscope – will also use significant data.

A lot of it is sort of the changing patterns in how we use our cell phones, said Cheng.

Verizon said, “We’ve talked with the customer who reported a $9,000 monthly wireless bill and resolved it to her satisfaction.”

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A company representative told KPIX 5 that customers with questions about their bills can call Customer Care team at 1-800-922-0204 or contact a rep by chat on