doo GmbH is running the platform doo.net and takes as a service provider over online-bookings, billing and payment handling for organizers of seminars, courses, advanced education or similar events. The credit card was probably charged due to an online registration for one of these events. After the payment you received a link to the doo booking portal, where you can download the associated invoice anytime. Additionally after the booking process an e-mail, about the confirmation of your booking as well as the invoice, was sent to the e-mail address stated.
If you still do not understand why your credit card was charged by doo, you can contact our doo booking service with the following information:
- Date of transaction
- Information about the credit card (holder, last 4 figures of the credit card number, type (Visa/Mastercard), expiry date)