Ameren put out a warning Wednesday to alert customers of a scam that cost them millions of dollars.

The utility company says scammers are posing as Ameren reps and calling customers. They threaten to disconnect electric service unless you pay using a pre-paid debit card.

The scammers even cloned numbers to make it look like Ameren is calling.

But, there are some red flags to watch out for. If the caller becomes angry, threatens you, or asks for a pin to get access to your money.

If you get a call, don't pay, hang up, and call your utility company.