Uber, the smartphone-based, ride-sharing service currently has an “F” rating from the Better Business Bureau (BBB), the lowest grade possible. BBB’s website lists 107 complaints filed against Uber in the past three years, most arising from disputes about its “surge pricing” practices where prices skyrocket during busy hours.

“Uber charged my card $710 for a nine-mile drive without notifying me of the surge charges that were in place at the time of my ride and will not refund,” posted one customer. Another wrote, “they charged me 9.5x what the rate should of been without any notification.”

It is unclear how long Uber has maintained its “F”-grade, but the New York Times first noticed it last week. According to BBB President and CEO Lori Wilson, BBB ratings are “constantly in flux depending on how and when the particular business responds to the complaints and other information posted to the BBB site,” PC World reports. Wilson estimates that the “F” has been there “for some time.”  

Uber insists that customers are always notified when surge pricing is in effect. Indeed, Uber maintains that surge pricing is the best method to get drivers on the road when demand for rides outpaces the supply of cars.

“Uber’s direct channel for two-way feedback is regularly reviewed and acted on to ensure a high-quality experience,” an Uber spokeswoman told the New York Times in a statement. “The fact is that consumers in 220 cities around the world have made their opinion known by taking millions of rides with Uber.”