A feature in the latest iOS 9.1 update is being blamed for driving a teenager's telephone bill from $250 to $2,000 and might just do the same for hapless iPhone users out there who do not know about it. Ashton Feingold, from Miami, Fla., discovered this too late, and now he faces his father's wrath for incurring the monthly charge.

The culprit turned out to be the Wi-Fi Assist feature, which automatically switches the phone to mobile data if the system detects a poor Wi-Fi signal. Feingold has been streaming and browsing the Internet in his room, which has poor Wi-Fi coverage. He thought that he was using his home's Wi-Fi service, but the device is already racking up more than 144,000 MB of data, CBS News reported.

Feingold did recieve a text message from his carrier, which notified him about the rate of consumed data. "It just said maybe 65 percent of your data has been used," Feingold told CBS News. It did not tell the iPhone owner much, so the message was ignored.

It is important to note that his experience is not unique. It already caused an uproar among several Apple customers who criticized the manner by which the Wi-Fi Assist was turned on by default. A group of users has already filed a class action lawsuit, arguing that Apple failed to adequately warn users with regards to how the feature works, 9 to 5 Mac reported.

Apple has released a support document explaining the Wi-Fi Assist feature and how it works. It is published in this page. But consumers point out that the move was already too late.