Maybe someone has already run across this...participant has medical bills and requests a hardship. Just about the time the money is direct-deposited, the hospital says "oops, that bill is too high" and adjusts it to some minimal amount.

Is there any way to un-do that?

How about correcting it as an "overpayment" under Rev. Proc. 2008-50?

Thanks, I'll try to keep that in mind for next time...it turns out there were other charges and now the payment is ok.