Actually, one of the things I'd said at the beginning was that the PHP code worked, and the issue I face is translating it into Perl.

Well, what you said was "The only working example I have for the SOAP sever I need to use is written in PHP". In my experience these services often provide examples written in various languages so my intention was to clarify. I don't know PHP so can't help you with translation.

You said too that "SOAP itself looks to be simple enough" but if you have a look at SOAP::Simple it says:

Let's face it. SOAP is painful. It's a dumb idea, the only reason you should ever consider using SOAP is if someone holds a gun to your head or pay you a lot of money for it.

Maybe that module should be called SOAP::Simple?

If you are familiar with XML a better approach may be to use XML::Compile::SOAP and it has lots of examples too. Without being able to see your Perl code and the details of how it fails the only other suggestion I have is to look through the many other nodes here on Perlmonks that mention SOAP and WSDL.