Depends on the particular case. For instance:
Customer says that they were on hold for an hour but upon looking at
the call logs they were only on hold for 14 minutes
In this case you still have an unacceptable wait time. So you treat the call the same way you do when any valid complaint happens.
People saying a task that's scheduled to run every 1 minute via cron
is only running once every ten minutes.
In this case, you need to gather more information. Is the job supposed to be scheduled every minute? Should it run that often? Why doesn't it? Is the a requirements document you can check? You need to determine if there was a problem in perception, a problem in the implementation not matching the requirement or a reason why the mismatch occurred (perhaps the job takes longer than a minute to run) and then determine if any action needs to happen. Usually I will say something, like the original requirement I have for that says for it to run every ten minutes. Has that changed? Do we need to change it?
People saying that an issue effects everyone when in reality only 1-2
people are effected.
In this case, this is generally used to push the priority of the request up. If the two people are senior managers or it is one of your largest clients, then you probably have to for political reasons. If they are not, then put it in the queue in the right place depending on the real priority and be on the lookout for this same person do do similar things in the future. Make sure that you talk to your boss about lowering the priority and why before communicating to the internal or external client. You don't want a complaint about this to reach him when he is unaware of what happened. Explain it based on other higher priorities not on the fact that he lied about the effect.
So you look for these types of lies and handle them differently.
If it is perceived pain and the pain was still valid, just ignore as much as possible and fix the cause of the problem. Apologize for the lengthy delay, explain what caused it and explain how it will be prevented in the future.
If it seems to be a genuine mismatch of requirements or misunderstanding, research and present findings in a neutral way.
If it seems to be deliberate to get more attention than a problem deserves, consider the political implications and talk it over with your boss.