You can log in to your personal customer account here. There you can view details of your booking as well as directly upgrade your Protection Package.
Click on "Protection Packages". There you will find an overview of your current package, the upgrades you can make and information that will help you understand the advantages of the Protection Packages at a glance:
Select the kind of protection upgrade you want and click on "Book now". As soon as you confirm the option, your protection package will be updated.
Please note: downgrading your originally booked protection package to a protection package with lower coverage is not possible.