(redirected) Dell Support failure

Hello, my 1st post and an apology to start with as this doesn't seem the ideal forum for my issue, but I can't find any better so please move this post to a more appropriate forum if one exists.

I recently bought a XPS 8700 desktop and have been trying unsuccesfully to get some answers from Dell Support to what is surely a very simple question. I am stuck in a loop of "not sales try tech - not tech try sales" type responses. Five contacts with Dell, email, phone, chat, all useless and no answer.

Copy of my question from email is -

"Hi I made a mistake when ordering my machine, I intended to order with Windows 8.1 Pro as I use Media Center which is apparently not available with standard Win 8.1. The standard Win version I have is working fine but can I update to Pro through Dell at advertised NZ$21.85 (considering only a few weeks old) or must I go through Microsoft at $169.00?"

Now does that seem like a difficult question? Apparently it is.

I'm at a loss as to how to contact Dell now to get some response, any suggestions or links to contacts would be much appreciated.