If three people misunderstood your message, the message might be the problem.

When one person reads something wrong, that is them. When several read it the same wrong way, the sentence is doing something you did not intend. Written messages carry no face or tone, so whatever you left out gets filled in by whoever is reading, and usually at the worst available setting.

If a message of yours keeps landing badly, rewrite it rather than explaining it again. Put the point in the first line, add what you want to happen, and cut anything readable as a dig. For anything genuinely tense, say it out loud instead.