You mentioned also a problem with time estimates. What was the real problem? Because someone being wrong isn't itself a problem.
The thing is, when I say a task will take X amount of time and the customer or boss thinks it should take less time than that. Normally I just say, "I'll do my best but I doubt I can get it done that fast" etc. It is just aggravating when people who don't know much about PLC's etc, and can't do the assignment themselves, basically imply that I'm too slow.