HOUSTON -- Parking boots have grown into a booming business in private parking lots throughout downtown Houston, Local 2 Investigates reported Wednesday.

Dozens of cars are being locked down with parking boots each day, leaving some drivers stranded even after they had paid the required fee, and Local 2 Investigates hidden cameras found a growing number of roving patrols in search of cars to boot.

Instead of the $5 to $10 parking fee, drivers are being charged more than $100 to unlock their cars.

"I don't like it. It ain't right," said Tiffany Plumber after her car was booted.

She and several others were booted after they said the payment machine failed to print a receipt for the money they had paid to park there.

"So they done made a good profit," she said.

A new city of Houston ordinance (Chapter 26, Article V, Section 26.264) makes it easier for private companies to boot cars on private lots, prompting a flood of online help wanted ads seeking people to boot cars and collect the cash throughout downtown Houston. Most of the positions pay the employees for each boot they lock onto someone's car.

In addition to cars being booted in lots with broken payment machines, Local 2 Investigates found cars being booted for parking over the yellow line or displaying their receipt upside down on the dashboard.

In many cases, drivers parked in private lots and paid a city of Houston parking meter a few steps away only to find out they should have paid the payment machine for that private lot instead.

"We looked and we saw that meter and we thought it was the right place to pay," said a Dallas man who was booted despite having paid a city parking meter and displayed the city parking receipt in his windshield.

This is a common mistake that is now costing drivers in a big way. The Dallas visitor coughed up $114, saying, "We think we parked correctly, we think we paid correctly, but what can I do?"

Samuel Castillo was booted after he said he paid a machine that turned out to be broken. No receipt was printed and he then waited more than two hours for an attendant to arrive and unlock his car.

He said, "I think it's wrong.  People are trying to do good and meet their appointments and trying to do the right thing by stopping and paying money."

The owners of private parking lots are now contracting with enforcement or booting companies to patrol their lots and lock down cars that are without the proper receipt displayed in the windshield.

A company called Equipark is among the new players in the arena. Chief Executive Officer Joe Martin said, "We're doing anywhere from 30 to 60 boots a day."

He admitted that he helped craft the city's boot ordinance while serving on the city of Houston Parking Commission.

"It kind of dawned on me that there may be a business opportunity here," he said.

Martin said he stepped down from the Parking Commission before the City Council passed the law to avoid a conflict of interest.

"We're trying to follow a model set by municipalities and we're in this for the long haul, not for a quick buck," he said.

His company has employees aggressively patrolling a number of lots all over downtown. Local 2 Investigates found them booting cars where payment machines were broken and, in one case, where the valid payment receipt was simply flipped upside down on the dashboard.

Martin said, "We're not trying to find a way to trick them. If we can see that that's a valid receipt, we're not going to boot them, but if we can't see that it's a valid receipt, it could be a receipt they picked up off the ground, it could be a receipt from yesterday, there's just no way of knowing until you see the other side of that receipt."

He said his company is no longer booting cars for being parked over the yellow line since the city ordinance is unclear on that point. Out of more than 8,000 boots since his company started one year ago, Martin said the Houston Police Department has only told him to refund six drivers. He said he has offered a couple dozen other drivers refunds without HPD involvement.

The city ordinance requires all violation notices and parking lot signs to list the phone number of the HPD Auto Dealer's Detail, which enforces the city's boot law.

An HPD spokeswoman said that unit is constantly fielding complaints and is working to make sure private boot companies are following the law.

She said any driver who feels they were booted without cause can call the HPD Auto Dealer's Detail at 713-308-2568, but she said they can only mediate disputes between drivers and private boot companies.

The city ordinance imposes several requirements for any lot that boots cars:

Signs must be posted warning that cars may be booted.
Attendants must be on duty at all times to unlock cars.
Receipts must be offered by a machine to prove that a driver paid the proper fare.
Receipts must contain the words, "Receipts must be displayed on dashboard."
Boot employees must pass criminal background checks and possess a license to boot from the city.
Booting companies must possess a license from the city and have a 24-hour phone number for booted customers to call.
Attendants must wear their city-issued license at all times and must wear uniforms with their company names.
Employees must perform their duties in a "courteous and professional manner."

Martin said the law also requires booting companies to respond within one hour when drivers call to have the boot removed.

He said, "Booting is half the price, less than half the time, and it's certainly less than half the anxiety and your car never leaves the parking lot."

He said the law allows his company to charge a $25 administrative fee to unlock the boots from cars after motorists prove that they had a valid receipt all along. If the driver is unable to prove they paid in advance, a fee of $100 is charged along with sales tax and the original parking fee.

One driver was upset at the idea of paying a fee despite proving that he had paid the original parking fare, saying, "I guess they just don't care. They just want the money. That's it."