@simsim
First, no need to worry, this is call Caller ID spoofing. You don't have anything compromised. On the other hand it is not something you can do or PM can do. It is happening to many people, and even CRTC has nothing effective to stop this
So, scammers did not really have access to your account or phone, they just make calls and use system to generate random fake caller ID to make the receiving ends believe it is a real calls and pick up the phone.
Again, nothing you can do. I always say it is like letter mail. People can send mail to something else but put your address as the return address. Not something you can do to stop or not something Canada Post can do or validate
Here are more info on this topic:
https://crtc.gc.ca/eng/phone/telemarketing/identit.htm
https://en.wikipedia.org/wiki/Caller_ID_spoofing
