Unlike eg: infringement notices, yellow work orders can be cancelled and withdrawn (by an authorised person, such as the issuing officer, or his senior officer after review, or by an authorised vehicle inspector) as they are not an auditable file. It is related to, but independent from any complaint file that may have ensued.

I have seen them cancelled same/next day quite a few times.

__________________
MY99 WRX sedan WRC blue Sold :(
MY99 WRX sedan Dark blue pearl :D
MY97 Liberty Outback Ltd Wagon
1990 Mk3 Supra turbo fully rebuilt 7M-GTE (Older son)
1991 Celica GT4 (Younger son)