Irritated customer

I have been trying to give 30 days notice to cancel my contract which expires next month. I have gone in store and was told that I need to cancel online. When online, it fails to process my request as it requires me to type letters as displayed in image. There is no image displayed on the site (Imaginary image maybe?). How am I supposed to cancel my contract? Its pathetic that this can only be done online, whilst the online platform is not very user friendly.