Go to admin >>> tools >>> Layout Boxes Controller

... and see what that sidebox is called.

or, look in your custom template /sideboxes folder for a sidebox name that resembles "shopping cart".

(It may be in template_default/sideboxes ... I don't know... look in both locations).

I think you have a custom sidebox there somehow.

Without being able to login to your hosting account, I can't be sure...