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OKLAHOMA CITY – An Oklahoma couple says they were taken advantage of by a door-to-door salesman.

The man was selling a cleaning product and the couple decided to purchase some of it.

They wrote a check for about $40, but more than $700 was taken from their account.

“That’s money they don’t have,” said Justin Siniard, the couple’s grandson.

Siniard’s grandparents are on a fixed income, but he says they have big hearts.

When a salesman came to their door pushing a cleaning product, they bought some.

“My mom, who checks their bank account to make sure everything is okay, sees a check for over $750,” he said. “From what we understand, the guy took the check and basically forged it for more than the amount, because the $40 check was never cashed; it was the same check numbers just for $750.”

We called the company, Advanage 20x, and spoke with a man claiming to be the general manager.

He said he was unaware of the issue and promised to investigate.

“I did try to call and I just got the run around and no one would call me back,” Siniard said.

Turns out the company has a D-minus rating with the Better Business Bureau.

“If a company is doing things correctly, they’re not going to have a D-minus rating,” said Ryan Ellis, with the Better Business Bureau.

Ellis says to be cautious when it comes to door-to-door sales.

“Remember they’re on your property, they’re on your porch,” he said.

Ellis says always take time to do quick research on the company or a product before you buy anything.

“If they’re a legitimate business person and they’re going to get a sale, they’re going to be okay and let you take five minutes to research them,” Ellis said.

He warns that you should be careful how you pay, saying cash is your best option.

“Never pay with a credit card. Never pay with a check. That gives them information about your private financial information,” he said.

After filing a police report, the bank refunded the couple’s money.

Justin just wants to warn others to watch out so they don’t become a victim as well.

“Somebody forged a check somewhere,”Siniard said.

When we called the company, they asked us to have Siniard contact them.

He did, and they told him they are now investigating.

The company’s general manager says they have a zero-tolerance policy regarding lying to or stealing from customers.

They assure KFOR they will make this right.

The Better Business Bureau says anyone selling door-to-door in Oklahoma needs a permit and you do have the right to ask to see that permit.