DENVER - Consumers call it predatory towing. Cars snatched up in a matter of minutes by tow trucks waiting nearby.

Businesses hire tow companies to keep spaces open for paying customers. 9Wants to Know found being a customer won't always protect you from being towed.

Posted signs clearly state parking in many business lot is for customers only. What you may not know, is the minute you walk out of a business, you are no longer considered a customer.

That means if you go somewhere else and don't move your car, someone else could be waiting to move it for you. A $5 dollar movie rental became a $200 dollar disaster for Denver resident Megan Kline.

"It was very predatory. I feel like I was victimized," Kline said.

Megan and Chris Kline saw the signs, but assumed they wouldn't be towed.

"I assumed if I was a legit customer of the business where I parked that I wouldn't be towed," Kline said.

They walked across the street to another business.

"We were in there for maybe 20 minutes and came back and our car was gone," Kline said.

The rental and tow receipts show they left Blockbuster at 8:09. The tow happened 19 minutes later at 8:28.

"The worst possible time," Kline said. "My husband just got out of the Army so we are scraping every penny that we possibly can just to make our rent."

The Klines had to pay $211 cash to get their car back, and they had to transport their 4-month-old daughter without a car seat, because it was locked inside their towed car.

"We actually had to pawn our TV to pay the tow bill," Kline said.

Blockbuster's regional manager Alfonso Garcia tells 9Wants to Know towing is the only way to guarantee customers have a place to park.

The lot, which is leased by Blockbuster and another business, has 13 signs warning customers if they leave, they'll be towed.

Stephanie Salazar with the Colfax Business Improvement District says businesses have to keep these spaces open, even if it means towing their own customers after they leave the store.

"Parking is at a premium," Salazar said. "If they showed preference to just one person staying in a spot, you're going to have everybody doing it."

She says the Central Colfax Corridor is Denver's most highly dense urban area, with about 55,000 people in a one mile radius.

"You're going to have a shortage of parking," Salazar said.

That's especially true on concert nights. 9Wants to Know saw tow trucks lined up along Colfax on a busy evening, hauling off car after car.

The Colorado Public Utilities Commission regulates tow companies and reports the number of transportation-related complaints nearly doubled in the last two years.

According to PUC spokesman Terry Bote, consumer complaints about towing, taxis, and other modes of transportation rose from 331 in 2007 and 2008 to 568 in 2011 and 2012.

The PUC is considering new towing rules, including making sure towing signs are well lit and clearly state who can be towed for parking illegally.

Kline hopes her hard lesson can help others avoid towing trouble.

"Move your car, because they will take it in a matter of minutes," Kline said.