Some weeks ago I wanted to deactivate my Twitter account. I hadn't used it for a while, and it claimed that my account was locked. Nothing was sent from it in many months, so it wasn't clear why/how it would be locked now.

For some reason you cannot deactivate your account when it is locked.

So I contacted Twitter demanding that as EU citizen (which is true) I hereby demand all data about me that Twitter or its subsidiaries might have, including account data, to be deleted under the GDPR... Or alternatively unlock my account so that I would be able to deactivate it.

They were actually pretty responsible. My account was unlocked 30 minutes later and I was able to deactivate it.