During my time
many drivers (including me)
suka suka
changed and cancelled jobs.... but never kena warning letter(s) on
this....
from my understanding, you will kena warning letter from
cancelling job now...

There are a few incidents, hirers bidded for reliefs (or via
visa), the other parties failed to go for corporate jobs transfers.
If guest is a Super VIP. Both (hirer & relief) can
gets immediate terminations.
There's one classic case, heavy downpour one day, this classic
driver last minute cancelled a
G-DEPARTURE without knowing the
consequences...
After few days, Comfort sent him a termination letter, reason is
because of his irresponsible behavious resulting in the
passenger,
...