Games moved from one account to another without warning - lost all progress as a result

Hi all,

For a good while (probably the last year or so) my Microsoft Store account and Xbox account were different and used different e-mails, like so:

- Account A was my Xbox account from 2010, and my main social account which I played my games with friends through.- Account B was the Microsoft store account
and e-mail I used to purchase Forza Horizon 4, my PayPal details, etc.

Today, I logged on to my computer, to find Microsoft automatically transfered my Xbox games from account A to B, including Forza Horizon 4. Very helpful overall, except that it made me pick out a new username and start a new social
account on account B. However, since it made me change accounts and account names, my save data, achievements and hours and hours of progress from Forza I had on account A are all gone and locked under a different username.

I still have access to both accounts, and a backed up set of files from before I opened the game post switch, but I don't exactly fancy putting 100+ hours in again for no reason.

If anybody has any insight or a way to transfer the save data to the new account, that would be just grand, and I am more than happy to answer any required questions or give the relevant details to an Xbox support team member.

Thanks in advance.

:)