I am trying to upgrade hosting and after I fill in the form and submit I get a message telling me my address is invalid. Can anybody help

I'm not quite willing to submit a form ordering upgrade to test things. But if you are told your address is invalid, chances are that your address is invalid. What address are you talking about? URL? billing address?

Assuming it is your billing address are you entering it EXACTLY as it appears on your credit card statement?

In both the US and UK there are occasional local problems where the official postal service address does not match local usage.