I use google pay. Is that NFC?
The more expensive one is a tap in for bus 145 at toa payoh bus interchange. For some reason, the tap in registered as a tap in for bus 145, but at Buona Vista Ter Bus Terminal instead. That's halfway across singapore! The tap out was registered correctly. So this trip ending up being charged to me as two seperate trips. The first one as a tap in at Buona Vista Ter Bus Terminal with missing entry, so i incur a full end to end bus fare of $2. Then get charged another fee for missing entry, and tap out at my destination.
The other one is probably more of bus captain error than card reader error. The bus took a wrong turn, and ended up lost. Went a pretty long distance, trying to find a place where it can U-Turn back to the correct route. Then when i was tapping out, i saw on the card reader, that it is showing the wrong bus stop (the tap out card reader supposed to show the current bus stop). It's probably tied to distance travelled by the bus. When i questioned the bus captain, he reassured me that the fare charged will still be correct. Spoiler alert: it wasn't, and i was overcharged.