Hmmm... I cannot promise you anything, but perhaps it would be worthwhile re-doing your account and adding an extra note explaining that the postal code is real. Perhaps you even have a form of ID/documentation where you can see it...?
Unfortunately, our low prices attract the usual suspects. We receive a very high volume of new fake accounts. Sometimes things that are actually real will raise red flags unintentionally. If we are not sure about an account's validity, we usually make the safe decision and reject it. We know that means that we lose customers, but it also prevents a lot of abuse.
As a customer with other online stores in the past, I have had my customer account flagged as fake because I have a last name that is unusual, because my home town's name sounded fake, and because people thought New Mexico was not part of the United States, so they thought the delivery address was fake.
Our team tries its best, but it's not perfect. We know we probably accidentally accidentally falsely mark some accounts as fake each day, and we are constantly trying to improve our system.
--Katie
Hmm... I wonder if there's a common postcode lookup software used in Germany that's to blame for this?
I recently moved house and had to update my details on Spreadshirt's [also a German co.] website. As with you, their site refused to accept my postcode was a valid postcode and wouldn't let me change my ddress. This also had the side-effect of locking my account.
After I emailed Spreadshirt about it, I had to go through the ridiculous palaver of them sending me a snail mail letter from Germany to my address in UK, containing a code which I had to then email back to them. At which point, they finally accepted that I [as the person who actually lives in the house!] might actually know my own postcode better than some database lookup software they were using in Germany.
Doesn't inspire confidence.