galley0,
I very often use "wreak havoc" in my speech. So I don't see what the big deal is about wrought havoc. I am confident that you can use it with confidence.
For what it is worth....
GuruNet.com
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play havoc
Also, raise or wreak havoc. Disrupt, damage, or destroy something, as in The wind played havoc with her hair, or The fire alarm raised havoc with the children, or The earthquake wrought havoc in the town. The noun havoc was once used as a command for invaders to begin looting and killing, but by the 1800s the term was being used for somewhat less aggressive activities.
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Company. All rights reserved.
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Hope that helps.
MountainHiker