What is the address to return KPN equipment?

Hey there,

I am moving abroad from the Netherlands and have cancelled my contract with KPN. Just yesterday I left my flat so now I don’t have access to it anymore. However when I left I still didn’t received the parcel to send my router back. That’s why I took the router with me to send it back from abroad, which will even cost me more money. But obviously I don’t know to which address I need to send the parcel!! 
where can I find that address now?

kind regards and thanks in advance 

anna