Well that form can be used for technical support there is nothing on there to suggest it is for paid versions.

If you go to this link https://support.avast.com/support/tickets/new, that shows an option for Technical Support and that is the direct link that I gave you.

What is the problem with Excel 2003 ?
Whilst I use XP Pro SP3 I have an ancient version of excel (Office 97) and no issue with that.