more than one bargained for
An unexpected outcome, especially an unfavorable one, as in Serving on the board this year has involved more work than I bargained for. This expression alludes to a higher than anticipated cost for a transaction. [Mid-1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.