If you are currently facing a login error on the client post here and we will change your login name (please note this is different than the display name) so that your client will allow you to sign in correctly. For example, if your name is currently Smart, we will add a 1 behind it so that you will now sign in as Smart1. By doing this you will appear on the forums under your original name, but will no longer struggle to sign in on the client. Hopefully this will work for everyone who is currently facing the problem, if you have any questions let me know.
Post below if you would like us to change your login name, thanks!