(WGN Radio) – Does a smart watch for $9, an electric toothbrush for $3, and a crystal necklace for $1.50 seem too good to be true? Those prices, offered in a flash sale on e-commerce site Temu, just might be.

You may recognize Temu from ubiquitous ads on Facebook and Instagram. The company has a U.S. headquarters, but is a “sister company” of the massive Chinese company Pinduoduo, reports Time. You can shop on Temu’s site or download the app, where you can also earn credits by playing games or inviting people to join.

About 50 million consumers have downloaded the app, said President and CEO of the Better Business Bureau of Chicago and Northern Illinois Steve Bernas.

Temu hasn’t just racked up downloads – it has also earned a C+ rating from the Better Business Bureau and 964 complaints lodged against it.

The Temu site offers deals ahead of Halloween, with costumes starting at 99 cents. (Temu via Associated Press)

Some people complain they got something in the wrong size, then weren’t able to get an exchange. Another complains the package they received was torn and the goods inside were all damaged.

“I placed an order with Temu for several items. I received duplicate items for some; didn’t receive another item I ordered (a tiered tray) and received only 1 piece of a 2 piece set,” reads on complaint with the BBB. “I tried contacting customer service. There is no phone # and ‘chatting’ has proved futile as there is an obvious language barrier. It’s so frustrating!”

“Company advertised a $1 promo for a $20 product and then deleted that item from the cart and left the others,” reads another complaint. “After I told them, they made up many excuses and after I followed their instructions and proved all their excuses as lies, they just said they wouldn’t give me it for no reason.”

Others complain the cheap prices are explained by poor quality items.

“We’re warning that many of these deals are really too good to be true,” said Bernas. “The problems are the products, concerns in privacy and identity theft issues. … You may want to seriously take a second look at whether you want this app or not.”

Hear more from Bernas in his interview with WGN Radio below.

A June Congressional report also unloaded a blistering critique of Temu another Chinese fashion retailer, Shein. Temu actually sued Shein this year, accusing its rival of violating U.S. antitrust law by preventing garment makers from working with it.

Lawmakers have also been trying to crack down on a century-old trade rule — known as de minimis — that benefits both Shein and Temu. Under the provision, imported packages valued under $800 receive tax exemptions and less oversight from U.S. customs.

The Associated Press contributed to this report.