GrabTaxi First Time Experience

Last week I was on the airport and about passed 10pm. I inquired a airport taxi service how much is the ride to Bacoor, Cavite and she showed me a fixed rate of Php2,100. So decided to try the GrabTaxi and after using the setting the destination and the metered fare was around Php600 so i confirmed the booking and the driver called me and explained me that the destination was to far and he asked me to give him an additional 200 to 300 hundred above the booked fare to cover-up the gas consumption, since he said that GrabTaxi office will question him regarding the large gas consumption, since my destination was Bacoor, Cavite. And since its rush hour and we've waiting for the GrabTaxi for 30 minutes. I agreed to the drivers offer. The driver was very chatty which i don't like. Since trying not to be rude I just chatted with him. After 30 to 45 minutes we arrive at our destination and the driver said its up to me how much additional I will give him. So I said to him just give me a change for P1,000 and he gave me P200 change. So I paid him around P600 quoted fare and plus P200 additional for gas total of P800. During morning when I tried to check my GrabTaxi app to review my trip last night, I was surprised that my booked trip was cancelled. So I called and GrabTaxi Support and asked out of curiosity why my booking was cancelled and also I asked why their drivers asking for additional gas on top of the metered fare. The support told me that under their "Driver's Code Conduct" drivers are not allowed to asked any additional payment beyond the metered fare and booking fee. GrabTaxi Support apologized and said they will investigate the report and will discipline their drivers. Overall GrabTaxi Service was Excellent, Fast Response and Safe Drive minus the dishonest drivers (he could just asked me for a plain tip and not make an excuse regarding gas consumption) and and also their drivers should were uniforms if not at least a polo shirt and long pants. The driver who attended me was wearing t-shirt and walking shorts and a rasta hat.