Factuur onvindbaar en rekeningnummer aanpassen

Hello @ockooi, welcome and thank you for your question! 

The first thing that comes to my mind is, if you are using your personal space: MijnKPN?

There you can find/ download all of your invoices of your subscription, add or remove extra options, change your personal info etc.
When you have registered an account, it is important to add your subscription to your MijnKPN account. You can do that by going to Menu → Producten → Koppel product en then choose for Thuis 
If you are home and connected with your KPN Internet, you only have to fill in the last 3 numbers of your bankaccount to add your subscription to your account. 

(If you are not home, you’ll have to fill in your customer number, zipcode and housenumber + the last 3 numbers of your bankaccount).

It is also possible to use the MijnKPN app!

You can also contact our Customer service, with these kind of requests: you can call us on Monday till Friday from 08:00 till 20:00 and on Saturday from 08:00 till 17:00 on 0800 0402 (free of charge). Please know that we are 24/7 available for technical problems.