Broken Xbox - account lost

My friends son's xbox has recently broken.

We have bought him a new one and he has tried to log back into his old account with the incorrect information and the microsoft account has now been locked.

Due to the age of the email address we are struggling to get the account unlocked with the security info we have provided, and we no longer have contact with the person who was put down as the alternative contact email. during our attempts to recover this
account my friend has now remembered the correct password for the email address. But due to the previous failed attempts, even with the correct password, we are unable to get his account back.

We dont see any other way forward currently other than making him start all over again but this would mean having to purchase all the games he has lost along with all the in game purchases he has made over the years tallying to probably around £200+.

Surely if we now know the correct password this is something we can get around in some way?

Its very hard to find a solution when dealing with automated services only!

Any help on this matter would be great

Thanks in advance

:)