Unlock Microsoft account

Hello,
at the beginning of this year I lost access to my Microsoft account which has Minecraft connected to it. First I thought it was a lost cause, but then I tried getting it back through Microsoft support, which sadly didn't help a lot. I have access to the Email used to create the account and various other ways to prove that Im the rightfull owner of the account. I then found the person in possession of my Account and after talking they agreed to hand it over to me with the new email etc.. But sadly the support locked my account while I was talking to them without even asking or telling me. I now have a microsoft account which is owned by me but I sadly cannot access it because support tells me, that something relating to the Security was changed and therefore they can't do anything about it, but also refuse to tell me what these Security features are (which were changed) and instead send me copy paste answers I have now received multiple times from multiple Support agents. I have also been told that it is possible to transfer it to a new Email which has sadly not lead to anything. Some help would be very much appreciated, because I have spent over 5000 hours playing Minecraft multiplayer and just creating a new Account doesn't fix it, due to the Account being tied to everything.

Thanks a lot in advance.
Simon

:)