I am no longer using KPN's Wi-Fi service. I can accept and pay the cancellation fee for one month after cancellation, which means I canceled in May and paid for June. However, I cannot accept paying the early termination fee.

When I subscribed to KPN last year, I was told that even though it was a one-year subscription, I could cancel at any time. However, the fees for early cancellation were not mentioned, which is unacceptable.

I was no longer in the EU when I canceled the subscription. When I subscribed to the WiFi last year, I was told that I could cancel at any time, but they didn't mention that I would need to pay extra fees for early cancellation. I am no longer using the services provided by KPN.

That's unfortunate Yueyi. If it concerned your first contract with us it's normally for a period of a year. Did you provide our contract and cancellation department with proof of your move?  

I have already left the EU. Do I need to provide a customs exit stamp?How do I provide these items?Can this method solve my problem? The remaining fees are unacceptable.

Normally if the the contract is still active you can provide a proof of deregistration from your local council and residence on this page: https://www.kpn.com/service/administratie/verhuizen/emigreren/doorgeven.htm .

Unfortunately the contact is already terminated so that's no longer an option. You can try to lodge a complaint with this form: https://www.kpn.com/service/klacht-of-vraag-indienen/formulier . You should provide your client number (klantnummer) en subject (internet/opzeggen) .

I can't guarantee  a favorabel outcome but outside of calling contracts and cancellation directly is this the best option. 

I'm trying to submit the form, looking for a solution