CHARLOTTE -- The Better Business Bureau is investigating a Charlotte towing company accused of being overly aggressive and arbitrarily raising prices.  We found out WheelBlockers has a history of complaints from people in the community.

"You feel so trapped," said Lizzy Ballard, who says a fun night with friends took an unexpected turn when they came back to a South End parking lot and found her car had been booted.

Ballard says they tried to ask a few questions, but employees with WheelBlockers got aggressive and even threatened them.

"They wanted the money right away," said Ballard. "There was no contesting. We just wanted to know if this was legitimate, and he said to [my friend], 'Keep talking and we'll raise the price $75 more.'"

Ballard isn't the only one who's had issues with the towing company.  20 complaints to the Better Business Bureau cite similar experiences. One person wrote, "This business is predatory and definitely corrupt."

"Actually within about the past month, they just went on what we call a watch list in our office," said Tom Bartholomy, president of the Better Business Bureau. "And that was because of the volume of complaints we've been receiving."

A manager at WheelBlockers told TWC News it's not surprising people are unhappy when their cars are booted or towed, but they should pay attention to the signs that are posted and not park illegally.  He also said everything the company does is within city ordinance for towing and booting.

The BBB agrees, saying so far they haven't seen any violations of city ordinance. They still plan to investigate the issues.

"They let them park, and as soon as they walked away they came and booted those cars too," said Ballard. "If you're genuinely trying to protect a parking spot, that's one thing. If you're just doing it for the money, that's another. I just don't think that's right."

Ballard wants to warn other drivers - if you see a similar towing sign and have any doubts or confusion, just don't park here.

"Just don't even risk it," she said.

WheelBlockers is accredited through the BBB, but its rating has dropped to an A- because of the recent complaints.  BBB has received 8 complaints about the company this year - 4 in April alone.