How do I return the old Motorola tv box to KPN?

Hi @Maarten Brandse , put the Motorola in a cardboard box.

You hand in this box at a PostNL location. Put your name/address and customernumber on a piece of paper inside the box, so that KPN can link the device to your address.

KPN
Antwoordnummer 10119
2400VB Alphen aan den Rijn

Sending to a “antwoordnummer” is always free. Keep the receipt which you'll receive from PostNL.