After numerous failed log in attempts using my SN account linked to Twitter, due to Twitter being down intermittently I remembered that SN now supports multiple log-in methods simultaneously.
So now once I was finally able to log back in to SN using my Twitter account, I then added my e-mail as a login method. So if (when) in the future Twitter is down again, I can just switch to logging in via e-mail.
Just though I'ld share this tip in case it benefits anyone else as well.