We've received your email and are working on this, so please reply to the email we've sent and we will endeavour to do this for you.
Redindus69, sorry for any confusion, but let me clarify in case you have not correctly read or understood our reply. We have not said we cannot change the username, but instead said that we cannot do this via the Matrix Helpdesk as you would lose access to the ticket therefore not see the replies we send saying this was done. Instead we asked that you email us about this. As there is no sensitive information in the ticket, I've copied my original reply to your first ticket below, and I had already copied and pasted this into the 2nd ticket you created
"I'm sorry you are having problems with this. The Unified Login, which brought all of the Slitherine, Matrix and Matrix Forum accounts into one login, was the first stage of unifying the accounts and sites. However the 2nd stage of the Unified Account is that users need to be using the same username and password across all of the sites, as going forwards we hope that there will be one login and one site. So no, you cannot have a separate username for the Member's Area and Forums.
We can change the username back, but cannot do this via this helpdesk, as it does affect things such as old tickets not being moved to the new account and PBEM games will also not carry over. So please can you contact us at firstname.lastname@example.org with the subject line including the reference(Matrix ticket number), and we will amend this for you."