In your account, open the most recent invoice that you have received from the company (only Telenet and De Watergroep).
Above the document, select the link Apply for/change mandate
Fill in the requested details and confirm with Apply for mandate
Select whether you want to have the document sent (by post), print it yourself or sign it electronically
Confirm your choice again or return to change it
In some cases, with a given invoice the company will not have provided the possibility to request a mandate. In that case you can wait until the next invoice or request the mandate directly with the company itself.