Third-party access via Organisational Link

Hi,

Previously when logging into my personal account on a Web Browser, it flashed up with what is the typically an organisational message about an IT administrator. 

After being ping-ponged back and forth from the Microsoft Support teams, it's been suggested there is an organisational link with my personal email account, which absolutely should NOT be the case.

My concern is if someone has linked my email with an organisational account, then they are privy to a lot sensitive information from personal finances to healthcare (this has also correlated with some odd behaviour on certain devices). 

The agents that I have spoke to have not yet provided me with a viable solution to removing any links to an organisational account, nor getting a list of any organisations or entities that have been linked to my personal account. 

Does anyone have any ideas as to a way around this? 

Many thanks.