Once you have set up an arrangement you can log in to your account with your email address rather than your reference.
You can do this via the ‘Log in’ link in the top right corner of this page (next to the 'Resolve debt' button).
If you are on mobile, click the icon below and then select 'Log in' from the drop down menu.
When you enter your email you will be sent a code which you can use to access your details.
If you need to make changes to an existing arrangement, find out how to do so here.