300+ People FaceTime Call From Unknown Number

I’ve received a Group FaceTime call which has 351 numbers in. I don’t know any of them but I am aware my number (and all the others) have been accessed from someone hacking our personal data from a shop I’ve purchased things from. I first tried deleting the call and have managed to delete the past one but the most recent is sat open at the top of my FaceTime list and only has the option “Tap to Join”.

I’ve tried deleting the app, turning my phone off and on again, turning FaceTime off in settings and none of this has worked. I’ve put my phone on airplane mode and tried clicking it every which way but I can’t seem to get rid of it.

As far as I can see online, you can’t even have a FaceTime call with more than 32 people so I don’t know how this is possible?

I don’t feel comfortable with it being open in the background so want to try and resolve the issue as soon as possible.

Any help you could offer would be greatly appreciated. Thank you in advance.