We were not able to use it at all in the one month that we had subscribed for it. Eventually when I tried to cancel it, like other reviewers here have said there is no facility on this website to do so, nor any pointer to how one can unsubscribe via worldpay.
But a google search for cancelling account on Worldpay lead to some good information on the Worldpay website. I was able to cancel my account immediately.
You can go to the WorldPay website_www.worldpay.com/shopper/admin_ and cancel account using Agreement Id from your payment details / user name and pwd.