Netflix payment started before I activated it

Hi ​@anoyaro and welcome to our KPN Community! That's odd, it's not supposed to be activated until you specifically order it. 

Did you not get an order confirmation from us two months ago? 
If you activate Netflix using your Combivoordeel and log in with the existing account, then everything should’ve transferred. 
Did you log in with the same account when you were walking through the activation?

If you did all that correctly and/or you didn't receive an order confirmation from us, then I suggest you make a call appointment with us. Then my colleague will be able to check everything with you!