Yes, this is possible.
Change your data via 'MyTroostwijk'. Log in in the usual way and click on 'MyTroostwijk'. Then click on 'Change your profile'. Then click on the arrow at the top right of 'Ú' next to 'Login details'. Now you can choose which part you want to change, for example 'Your contact details'.
In Belgium, the invoice can only be adjusted within two weeks after the closing of the auction, contact via firstname.lastname@example.org.