ALBUQUERQUE, N.M. -- Marie Hernandez only planned to pump $20 worth of gas last Thursday, but said before she knew it her tank was full and she got quite a deal.

"I was about to go in anyway and ask why did this stop at $6.40 when she comes running out and grabbed the tag and said I needed to go inside and pay for the gas," Hernandez said.

Hernandez said she almost didn't notice the mistake, but that management told her they under charged her.

According to her receipts she first paid $6.40 for 17 gallons of gas. That's 36 cents a gallon. But she said she was charged another $62 when management found out -- that's $3.79 a gallon.

"I put my card in there in good faith. If it would have been running at the proper amount I would have put what I needed in and left," Hernandez said.

"So they made a mistake and made you pay for it?" asked Target 7 Investigator Mitch Blacher.

"Basically, yeah," Hernandez said.

Target 7 went to talk to the gas station's management.

"Hey, do you work here?" Blacher asked.

"Yeah, I'm the manager," replied the station employee.

After the manager was asked about the situation she said to go inside and talk to the area manager.

The area manager referred Target 7 to the station's corporate office. So far they have not responded.

But Hernandez said Target 7's attention must have got their attention. She said the corporate office offered to reimburse her for the mistake.

If you find yourself in the same situation, remember you only have to pay the price posted on the pump.

The Department of Agriculture, which regulates gas stations in New Mexico, said it's unethical to make a customer pay for a misposted price.