You can log in to your personal customer account here. There you can view details of your booking as well as add equipment to your booking:
Click in the navigation on the left on "Equipment". There you will find an overview of the available equipment:
Select the desired equipment and click on "Book now" on the right side. The equipment will be added to your booking as soon as the payment is confirmed.
We have a fixed number of accessories available, depending on demand and the station. We adjust this every season to meet demand as much as possible. Unfortunately, some accessories may still be unavailable and you will not see them as an option to add to your booking. In this case, we are unable to provide any additional extras. We appreciate your understanding! Please always check the respective booking to see if the desired accessories are available.
You can find a list of existing equipment here: What equipment does my camper offer?
Please note, you can't cancel equipment in your customer account on your own. Check the following article for more info on this: Can I cancel booked equipment?