Hacked Facebook contact

Hello,

One of my Facebook contacts, my aunt, was hacked. The hacker asked me to send him my phone number, which I did; nothing unusual so far. Then she said her phone is blocked and that to recover her PIN code she needs to send it to my phone, and if I’m willing to send it. I should have sensed the scam, but I sent the code. Then I receive a text saying that 550 euros were charged by mistake to my phone line. My aunt, the hacker, says, "oh sorry, an invoice arrived by mistake; they’ll send me a refund form and we’ll fill it out together, do you want to?" And that’s when I realize the scam. Her phone is on voicemail and I can’t warn her. I’ve alerted our mutual contacts and family to try to reach her. I don’t know if there’s anything else I can do? Thanks for any advice you have…