I also had a similar experience... Once I was waiting for bus to
take me from Bedok North Avenue 1 to Bedok Interchange. A 87 came
and stopped, but the bus was full. I saw a 60 behind and it was not
full, so I flagged to the 60. But the 60 driver, seeing the 87 in
front, point to the 87 and then skipped the bus stop. Feeling
lan-lan, I went back to the 87, but the 87 driver refused to open
the front door because the bus was full. So in the end I missed 2
buses... Luckily, minutes later I was "rescued" by an empty 17A...
When the 17A turned into Bedok Interchange, I saw the 60 leaving
the interchange, and I gave an angry stare to the 60 driver... (At
least I'm courteous enough not to show my middle finger) 