I would like to change my subscription into prepaid

Hi ​@Dania bisher, 
First of all, we're glad you've decided to stay with us as a customer after ending your subscription. This is of course possible and free of charge. Your annual contract must have ended first after which you can switch to prepaid with a one-month cancellation notice.
In that case, please contact us. It's important to clearly state that you want to switch to prepaid and not just cancel your subscription. You can do this by calling 1200 from your mobile number. Alternatively, you can easily schedule a callback appointment (bottom right corner), we’ll contact you at a time that suits you to resolve this. This also helps you avoid any potential waiting time.