iPhone remotely hacked and cloned

My Apple account was remotely hacked. Somehow an individual(s) were able to remotely gain access to both my Apple ID and device. They managed to override my own mobile number by replacing it with theirs. By doing this these individual(s) took complete control of my device/phone number. I believe the term for this is “device cloning”? Somehow they were capable of doing this without my knowledge.

Does anyone know how this could be possible or experienced something similar? This unknown phone number was never visible when searching through my Apple account or device.

Early 2018 I noticed odd things happening to my iPhone, for example the iPhone not keeping charged battery. This was easily dismissed due to announcement of battery problems. One day I turned my iPhone’s location feature off and an unknown telephone number remotely placed my iPhone into lost mode. I was locked out of my own phone.

This was an unknown phone number that has no known association with my Apple or carrier accounts. I immediately contacted both companies and reported the incident. During the call with Apple Support I followed all instructions on re-securing my Apple account which included changing my password. I was instructed to go through settings, login to my account with my new password, etc.. At the end of this call I was “reassured” by an Apple Support Supervisor that my account was now safe.

The following day I attempted to login to my Apple account through the Apple website. This was my first attempt at logging in that day with my new password. However, I was unable to gain access. Apple’s website stated that my account was locked, being evaluated and within 3-days I would receive a verification code texted to the number listed at the bottom of the screen. The number listed was not mine. It was the same number that had remotely hacked my iPhone the previous day. 

The same hacker was able to gain access to my Apple ID and change my password less than 24-hours AFTER reporting and re-securing my account with Apple Support. How is that possible?

No one has direct access to my iPhone. It is password protected. I do not use any other devices (mac, iPad). I have not shared my Apple ID or password with anyone. My account has always had 2-factor authentication enabled. I never click on strange text or email links.