偏勞

undue trouble / Thank you for having gone out of your way to help me.

to lean / to slant / oblique / prejudiced / to deviate from average / to stray from the intended line / stubbornly / contrary to expectations

to toil / labor / laborer / to put sb to trouble (of doing sth) / meritorious deed / to console (Taiwan pr. [lao4] for this sense)