I just wanted to cancel my paid e-mail account at gmx and switch to the free version as I use gmail and this domain for e-mail now almost exclusively.

As you can open almost every paid account there online without signing anything, I expected that this would be the same for cancelling.

But no, that would be too much service, wouldn't it?

You have to fax them a reply with your signature in 5 days to have an account canceled! That's service for you in Germany!