The Anchor Networks head sysadmin has an opinion on commercial support for software that's pretty similar to mine - it's garbage. Both of us have learned this from painful experience.
The post is well worth a read if you're in a sysadmin/tech line of work. It mirrors my experiences with several vendors very closely, except that this particular case doesn't include any inter-vendor buck-passing or blame games. There's a reason more and more of the systems at work run on software I have source code to and can rely on myself to maintain - because that way, things actually get fixed.
If you think Anchor's experience with dedicated commercial support organizations is bad, you should try contacting tech support for incredibly expensive commercial software you've licensed and asking them to support their product! I've had totally disinterested or completely useless support from vendors of ten thousand dollar software packages. After all, just because I paid for it doesn't mean I should expect it to work as advertised or expect them to be interested in fixing bugs, right?
Adobe, Quark, MYOB, Apple. This means you.
Anyway, the downside of doing all the support work in-house is that you need to have the skills to undestand and run the systems you use. You can't run a DNS server if you don't understand DNS, can't run a mail server if you don't understand IMAP,SMTP,POP3 and TLS, etc. However, given that vendor support seems to be totally useless except for problems a retarded monkey could figure out, it's beyond me how people with no understanding of the systems they work with ever get anything done, whether or not they're paying for support.
Maybe they don't? It'd explain a lot about many of the businesses I work with...