Someone hacked my and family’s FaceTime- please help

My mom, sister, aunt and I have a normal group chat. Yesterday, my phone said that my mom was calling the group chat on FaceTime. I answer and instead of my mom, it’s an Indian man saying hello. They called multiple times. An hour later, it was just my mom FaceTiming me right after she texted me something so I assumed it was her and answered. It was still an Indian man saying hi. It’s the weirdest thing. My aunt told me that I FaceTimed her yesterday as well and an Indian man was on the other end of the line. I’m really creeped out over this. I called Apple and they said that something like that is not possible, and they have no clue what this is or how it happened. We changed our Apple ID passwords and put to sign out out of all other devices. No other devices other than ours were listed in the settings. I didn’t get a pop up message that my Apple ID is being used somewhere else or anything like that. Has anyone experienced some thing like this? I don’t really know what to do about this.