I see the Buy Now button on the product you linked to, have you correct this already on your own? I'm not seeing the title either, however.
Can you try testing for a plugin conflict? So you'd deactivate all of your plugins except for Exchange and then see if it works properly. If it does, reactivate your other plugins, one at a time, testing Exchange each time to see which plugin is creating the conflict.
You can also test to see if there is a theme conflict by temporarily activating one of the WordPress default themes, like Twenty Thirteen.
Give that a try and let me know how it goes?
Thank you, I did manage to get the buy button working and someone has changed the code so that the title shows too, so this is now tfixed thank you. However the downlaods now aren't working, so I have submitted a different ticket about this.
Thank you for your help.