If it sounds right to an idiot, it's very hard to break him of his habit of saying it incorrectly. I know many people who freely interchange Austria and Australia, say things like "most biggest", and think that the words turret and faction are just typos for turrent and fraction.
The point is, the only way you can break them of the habit is to lead by example. Keep pronouncing it right. They'll catch on. If not, like many other Anons have said, just link them to a basic Japanese phonetics chart.