Always better to call. Otherwise, they will ring the day before to confirm your location and so you can do it then.
No problem in Singapore (Sixt) or Melbourne (Hughes). I agree with Zol, I just tell them the day before when they call to confirm what the arrangements are. I've picked people up on the way, diverted to pick up an item on the way etc and always no problems. Of course it helps if you tip the driver
before you set off. They seem to always nod with a smile and agree to your request
