URGENT: Magento Sagepay Ebizmarts Extension Problem

We have an install of magento (1.7.0.2) and we have installed Ebizmarts Sagepay extension. We cannot however get it to work. The site either gives an error saying 'your card has not been charged' OR the site processes the order without sending the person to Sagepay to make payment, so the order is placed but no payment is taken. We are using the Sagepay Form method (where they are taken to sagepay to pay) Please only bid if you have worked with this extension and sagepay before! We need a fix asap!