Being the original author of the suggestions around social skills, let me add some more around this subject.

When contacting a helpdesk agent and "telling" them what to do, or what one's rights are, one immediately has lost a large amount of credit with that agent. You only have one opportunity to give a first impression.

Just describe one's issue, let the agent figure out what to do and only once the agent can't solve and is running out of options, give very subtle hints, what might be additional options, hugely avoiding showing of one's knowledge (with the subtle suggestion, it's significantly more than the agent's one).

Difficult for some people, though so very important, when you want to accomplish something around a difficult subject.