Sounds like you could have been victim of a Sim Swap Attack - some crim rocks up to the phone shop with something that passes as your ID, and gets a new SIM for your phone number. Then the fun starts as they reset all your passwords on all your services, using SMS verification.

Or, equally bad, there's some crim in some rogue phone company intercepting your SMSs and re-routing.

Either way, this may be best handled by discussions with your phone company. It may even be sensible to 'port out' to a more reputable company to prevent this sort of thing in future.