A few times i encounter some irresponsible / assholes passengers which climbs above my head.
Examples:

1) Passenger cutting her finger nails at my back seat. I noticed it during the ride, but just dont wanna complain directly to passenger.
2) Students sitting more than 4 passengers behind, and still ignores (and gives a innocent smile or innocent remarks) despite being told off that it is not allowed. Cant cancel as i already arrived pickup point.
The worst one is those using promo code  . He / she must be thinking - What a bargain. RM 1 to sit 5 people. 

3) Passenger request drop off her friend first at her friend's hostel before proceeding to drop off point. That time multi stop was not introduced, and worse still, using promo  code
4) Passenger sit 3 + 1 passenger , using Grabshare. Since drop off point is nearby, so i just close one eye , since i already arrived.

5) passenger called ask me where am i, i said, i am 200m away, he acknowledged and even give me house number. arrived at his house gate, his wife came out and told me he already left and already heading to the airport (but booking states, Drop off at Taman Desa Medical Centre). Okay wtf. Call his phone, ringing, refuse to answer 

These are the few incidents i can recall.

A number of times i reported to cs, and its either "we will investigate and take necessary actions" or "we will remark in the system", especially the latter one is not very convincing. Ok, so what happens next?

Seriously grab customer service response isn't as convincing as Uber. They don't respond as well as Uber.
I think their FB team is just a group of sweet talkers.
But the reason i still stick with Grab is because of their incentives (Im a Ambassador) and fare prices. I havent compared Uber's Cash King yet, but every time a heavy Promo comes on board, some passengers literally abuse it, especially students.