This is often because you simply signed up with the wrong email address.
If you have more than one address, you can simply try the second or third alternative.
If that doesn't help, you can check if the spelling was correct.
Does the e-mail address really end in ".com" or in ".de" or something completely different?
Was it really the right combination of numbers or is there a transposed digit?
Otherwise you can of course contact us via email@example.com and we will investigate the matter together.