There's actually one direct flight to Colombo from KL tonight, but it's delayed:
CMB Colombo MH179 23.05 - 23.59 (scheduled) --> 00.10 - 01.05 (new schedule after getting delayed)
That flight has actually landed. I thing it was from yesterday and delayed past midnight, so shows up for today. At least that is the way I read the chart.
Three possible flights from Singapore to Colombo
1) CX 711 9:00pm -- 10:25pm
2) SQ 468 11:05pm -- 12:15am
3) EK 349 10:05am -- 1:40am
There are lots of flights from KUL to SIN. If that spec about the team at a travel agency is correct....might sense, since flights are split between the M terminal and the L Terminal at KUL