Written out longer than the summary on the home page — for the people who want to know what the workshop does with the request between the moment the button is pressed and the moment the balance shows up on the SIM.
The form lives on a separate page, /recharge.html, on purpose. The home page is a description; the form is where the request is composed. Three fields matter: the prepaid Ortel Mobile number in German format (+49 followed by 10 or 11 digits), the amount (15, 25, 35, 50 € or a custom value between 5 and 100 €) and an e-mail if you want a written confirmation.
Submitting the form redirects to payments.guthabenwerk.org. The amount, the currency (EUR) and the order id land in the URL query string — no hidden fields, no double conversion. Card details are entered only on that page, never on this domain.
The checkout runs a standard 3-D Secure step-up: your bank shows the prompt in the mobile app or by SMS, you confirm once. Visa and Mastercard are supported; cards starting with 3, 6 or 35 are declined at the form stage with a clear message.
Every accepted payment lands in the workshop queue at Pacellistraße 10 in Altstadt-Lehel. During Mon–Fri office hours a real person checks that the amount and the prepaid number match, then applies the top-up on the operator side. Outside office hours the order queues to the next working morning.
Ortel Mobile updates the prepaid balance a few minutes after the workshop pushes the top-up. You receive a confirmation e-mail with the order id if you filled that field. Reply to that thread if anything looks off — the same crew that took the order also reads the replies.