Unfortunately, not all banks allow payment with Sofortüberweisung. Please ask your bank directly if Sofortüberweisung is blocked or if you have to activate this payment method for your online banking.
Alternatively you can pay with Paypal, maybe you have someone in your family or friends who can pay for you if you don't have an account at Paypal. Additionally you can pay with your credit card (Visa & MasterCard) if it supports 3D-Secure.
If you have a debit from Sofortüberweisung without finding an order afterwards, please contact us with your full name, a screenshot from your online banking and the time of the payment.
You can find more information about payment methods here.