I am sure your problem here @Cjp2k will be due to the broadband number being your main account and the SIM only being attached to the same online account. When you cancelled your broadband, it will have knocked out the remaining SIM only contract on the same account.
Unfortunately, this is going to mean you will need to set up a new pay monthly account for the SIM only contract. As far as is known you wouldn't be able to use the same log in information as you had used when you had the broadband and you will need a new user name, password and most probably a different email address. When the new online account is set up, you will be able to link the Application. It is recommended to clear cookies and PC cache before setting up the new account.
I would recommend speaking to the Social Team for account access and direct help and support, if you use social media just follow this link: Contact Us Alternatively, there are the customer service channels of 191 and live chat.
