NEW YORK (CBSNewYork) — An elderly woman wants to warn others after she says she was scammed out of tens of thousands of dollars. What she thought was a prize-winning phone call proved to be much more sinister.

“Mrs. Shirley listen to me, and listen to me very carefully,” the alleged con artist said in a voicemail to the victim. “This is very important. We need to get to you and we need to get to you ASAP.”

The man who left the message is allegedly responsible for stealing more than $20,000 from 90-year-old Shirley Donohue.

“Why? Why did they do it to me? I didn’t do anything to them,” the heartbroken victim tells CBS2.

Donohue says it happened a few months ago, and started with calls and voicemails from a strange man telling her she had won a Publisher’s Clearing House competition.

“Please do not disappoint me,” the voicemail said. “Pick up the phone and give me a call right now.”

To claim her prize, the conman said she simply had to call back and mail the money in cash between the pages of a magazine. In return, she’d get her money back with her cash prize.

“I was very gullible, so I thought they were on the up and up,” Donohue said.

So far, nobody has been caught. Donohue says she’s sharing her story so it doesn’t happen to anyone else.

“It upsets me,” she said. “I feel a senior citizen, who’s living on a certain amount of money to begin with, retirement.”

Phone scams aren’t a new phenomenon. It’s a problem that AARP says costs Americans about $9.5 billion dollars a year, but there are things you can do to prevent them.

“Publishers Clearing House doesn’t call people about their rewards,” Better Business Bureau Vice President Luana Lewis said. “They send someone in person, or they send a letter.”

One of the best things experts say you can do to prevent it from happening to you is check in with someone you know before you take any action. It could save you a lot of money.

Also, if you’re told you won a lottery that you’ve never even entered, it’s most definitely a scam.

AARP says nearly half of all mobile calls will be scammers by 2019.