Hey there. Unfortunately Bungie is unable to modify existing accounts. You will unfortunately have to keep working with PlayStation to find a way to regain/re-establish access
[quote]Destiny Player Support and Bungie cannot modify or remove accounts linked to Bungie.net profiles. To protect player privacy and data, you must be able to log in to any linked accounts to prove ownership prior to modifying your linked account. If you no longer have access to a linked account, you will need to reach out to the specific platform’s support for assistance with account recovery options.[/quote]
https://help.bungie.net/hc/en-us/articles/360049498031-Destiny-2-Cross-Save-Guide