Another annoying trick by tech / customer support is: first person asks all the details (wastes your time) , than say you are in wrong department and transfer you, than the next person asks for all details again (waistes your time) ... transferes you ... untill you have no time left and give up while on hold.
Well in all honesty. Most of the time the agent wants to really help (if that agent does have the knowledge) but it's the rules enforced that determine how help such an agent can be. The comic here is a good example of bad policy. About companies that drop support on their product the second warranty is gone and it can be gone very very soon according to their rules.
The usefulness of a help desk is determined on marketing strategy. Bottom marked strategy (cheap products with short warranty) tend to have a help desk merely because it's supposed to be there, not actually to 'help'.