Locked out of Hotmail and no longer have access to old phone for PIN (10 year account)

My brother has been locked out of his Hotmail account (which he has owned for 10+ years).

He no longer has access to the contact number associated with the account so requesting a reset pin is not an option.

We've tried numerous attempts at the automated recovery form, with no joy.

My only option now is to perhaps speak directly to a Microsoft representative who might be able to manually unlock the account with any other details we can provide. I've tried 100s of links on the Microsoft pages to try and speak with an actual person, whether via Live Chat or a Call, but it just keeps sending me around in a loop or suggesting I resolve my issue via the community help.

His phone (Android) still has the account added but keeps mentioning he can't login due to suspicious activity.

I'm at the end of my wits - He really needs access to his email, all of his banking, bills, social media accounts, etc, are attached to this email.