The requested overstapservice from Ziggo to KPN did not work

I am a new KPN customer since December and I have requested KPN to handle my cancellation at Ziggo 

This is clearly shown on the email confirmation I have received after my purchase, however no cancellation request was sent to Ziggo and as result I am still receiving invoice from my old provider.

I have called Ziggo and after one hour  they concluded that it is KPN fault and they can't help me, upon my request they have terminated my subscription but this  will only happen after 1 month of notice period

I have called KPN customer support and after another hour of waiting in line my call was transferred to another department (billing) and then abnormally disconnected while i was waiting. 

I have contacted che KPN Chat service and after proving my statement by sending the confirmation email of my purchase order (clearly showing: Overstapservice Provider: Ziggo) they  explained I did not click on a confirmation link i should have received on December 11

I have checked my mailbox and on that that and 4 different emails were sent by KPN, however none of them has a confirmation link that I should click to confirm something. 

To conclude my customer experience is the worst ever, I cannot believe that I request a service but it is not activated unless I do not click on a validation, at least I would expect clear  notification for this.