There were messages from iDrive coming in by mail, but no question or even better an automated sync stop before confirmation. Unfortunately these mails were automatic sorted so that I didn't get them in time.
I guess it's part of their business model where they earn quite a lot of money even they lost me as customer. It was similar in Europe with mobile plans, where they charged you whatever they wanted until it was capped to a max of 60 €/month.

At least I learned out of that, that I have to be more careful with some things.