There are more suitable routes to go through to get satisfaction on a support issue than the telephone... But since it's the modem that caused your problem it would be a bit like the old "in the event of network problems contact us by email" joke.
On the other hand, however, PC assembly is not for those who simply want to save money on the entire unit. It's not a simple thing, and if one thinks about the complexity of an operating system, PCI/BIOS/other hardware foibles, and the combination of the above, one's time is best spent looking for a *qualified* tech person to do the assembly and installations for them.
The IT sector's most neglected question is often "How much is my time worth?" - and since PC assembly isn't exactly something one can master in an afternoon, non-technical users need to ask themselves how much time they might spend in comparison with someone who isn't just putting together PCs in their spare time.
This is not a belittling comment, but a fact of simple time management involving expertise. I wouldn't expect to be able to write as good a Will in as little time as a good solicitor/lawyer could; as good an investment plan as a qualified investment advisor; or as good a damp-proof course as someone who does this for a living. While the DIY spirit has indeed motivated many people to excell in the IT arena, it's not until much experience has been assimilated that one does more than learn.
It doesn't help that one of the most difficult problems IT has in the UK is that the business has been populated with what they call "cowboys", much like the masses of plumbers who still aren't CORGI-registered and don't charge (or pay!) VAT. Most of these folks are only interested in the short-term benefits, ie money, and NOT interested in the slightest in helping others. The IT sector is a Service Industry, and not just a fast track to fame and fortune, but don't tell these guys. It's no wonder as a result that technical consultants in the UK are finding it difficult to survive (though the government's ongoing campaign to make us all 'simply go to the JobCentre' despite no IT jobs being there doesn't help). Since moving to London in 2000, I've learned that IT consultants have probably as bad a name as the hack jobbers who pretend to be painters-decorators but have never learned anything about the kinds of paint required for external use (in many cases they deserve it); and given the nature of people to assume the negative by default, especially when there's so much of it about, it's easy to think "Where else do I go?"
I don't unfortunately have an answer for that question unless one is in my part of town. I also won't try to apologize for the poor social skills of otherwise-expertised people on the phone "at Microsoft", and would recommend complaining to them in writing as opposed to email, which is still quite ignorable to many people, and still not accepted as a legal form of notification.
If they don't hear about it, it's not a problem, yes?