How to delete a directory service that wont be deleted

I have a directory service created when a Workspace was created. The workspace has subsequently been removed. When I go to delete the directory I get -

"You are trying to delete the directory "corp.amazonworkspaces.com (d-XXXXXXXX)". This directory still has associated resources attached to it and can't be deleted until the following steps are taken:"

When I go in to Workspaces I can see the directory, but when I go to deregister there I get

"An Error Has Occurred. If you continue to experience an issue contact the AWS Support Team on the community forums and via AWS Premium Support at: AWS Support Center ."

the aws cli says this [cloudshell-user@ip-10-2-53-104 ~]$ aws workspaces describe-workspaces { "Workspaces": [] } [cloudshell-user@ip-10-2-53-104 ~]$

and if I try to deregister the directory

[cloudshell-user@ip-10-2-53-104 ~]$ aws workspaces deregister-workspace-directory --directory-id d-xxxxxxxxx

An error occurred (OperationNotSupportedException) when calling the DeregisterWorkspaceDirectory operation: There are WorkSpaces assigned to this directory. You must remove the WorkSpaces before you deregister the directory. [cloudshell-user@ip-10-2-53-104 ~]$

trying to delete it does nothing

[cloudshell-user@ip-10-2-53-104 ~]$ aws ds delete-directory --directory-id d-XXXXXXX

An error occurred (ClientException) when calling the DeleteDirectory operation: Cannot delete the directory because it still has authorized applications. : RequestId: f8c87176-eb11-462f-86cb-826c3bca70be [cloudshell-user@ip-10-2-53-104 ~]$

I suspect the cause may be a deleted dns entry from long ago. I dont know how to move forward with this, any help appreciated

Charlie