What is the website url? I'll see if I can spot an issue. If you give me FTP access then I could try making any necessary changes.
The key to fixing any problem is to figure out why it occurs. I doubt 30% of Canadians have javascript turned off. You could hide the button by default and display it with javascript to make sure that isn't the cause. You could also add a session check to make sure it never happens. If you send me a URL to reproduce the issue and FTP access I'll help you implement it.