Epic Games complaint: 8 year olds email fogotton

my 8 year old created an epics game account but forgot to write down the email address that was used to create the account. Obviously as his mum he used my email address for the parent conformation. We have been trying for over a month to retrieve the email from epic games but they are refusing to let us know what email is linked to his account. We have sent over 70 pieces of evidence showing that it is our account. I have been emailing them through my email which is the email that ed the account. So they know 100% that we are the legitimate owners of the account. I explained that he is 8 and of course didn’t think to write the email down.
We currently have access to the game itself but our concern is ifwhen the Xbox needs replacing, we wont be able to access the fortnite account because we don’t know what the email is to it. It has 3 years of collecting and buying skins etc. on it so is worth a lot of money and he is devastated we may never get back into it.

The emails between myself and various staff at epic games have been going on for over a month with no budge, even though the evidence shows we are the owners of the account, they are refusing to tell us what email is linked. We have even sent videos of us playing live on the account but still no budge.
One minute they are telling us it is a ghostguest account ( no informationemail linked to the account) , the next minute they are telling us there is an email linked but they cant tell us for security reasons. They have asked us to send all our emails so they can check for similarities on the email that is linked to his account. I know for a fact there would be similarities because we keep all of our emails roughly the same with one or two letter changes. Still no budge.