Fix GPS quote tool on website

Please go to this link: [login to view URL] On the right side of the website you will see a 'get a quote' panel (you will have to view in chrome or internet explorer as it does not work properly in firefox). This is for UK postcodes (zipcodes) only, and is used to generate a quote for a parcel delivery (user enterscollection and delivery postcodes) This works fine 90% of the time, but sometimes it shows the quote as £0 (as shown on the screenshot attached). I need someone to fix this so it works 100% of the time. There will be further projects on this website as I have many issues that do not work on this site.