"It just said maybe 65 percent of your data has been used," he told CBS4.

Feingold did not think much of it and continued using his phone as usual.

"(The bill came) and it was over $2,000," Ashton's father Jeff Feingold said. "Usually it was about $250 a month."

"I thought my dad was going to kill me," Ashton Feingold said.

It turns out that Wi-Fi Assist is to blame.

Wi-Fi Assist is a feature that is available on iPhones running operating system 9.1 or higher.

The feature automatically uses data when Wi-Fi signals are weak.

Feingold's bedroom has a weak Wi-Fi signal. Because the feature is on by default, he was using data when he thought he was using Wi-Fi.Feingold ended up using 144,000 megabytes of data.

CBS spoke with Mike Campbell of Apple Insider, who said, "It comes by default, it's switched on, that's part of the reason why there's kind of an uproar."

Apple's support site says users might use more data with this feature, but "for most users, this should only be a small percentage higher than previous usage."

To turn off Wi-Fi Assist, users can go to their settings app, then cellular and scroll down to Wi-Fi assist, switching it off.