Ok -this is exSIN specific, so perhaps OT, but figured still a comparison point between the 2 airlines..
So both airlines have buggy websites, but SQ's has been in that form for a while now.
I tried to make a credit card specific promotional fare booking exSIN last night (friday) on a new ANZ card that I have. It was a V class are not available under any of the many other card related promos that they are currently running (and also unbookable in that fareclass without the promo).
I kept getting an invalid card error on the CX website, perhaps due to a system upgrade at ANZ's end (who were, btw, unreachabale for the most part).
Figured that I was SOL, given this was a SIN specific card promotion and their SIN reservations line was closed till monday.
Ended up calling CX's HK call centre on a whim (the 'international access no' had a real poor connection, though I think its all the same call centre) and guess what?
Not only did they get me the exact same fare, I was met with a 'no problem lah' (think she was trying to just be endearing to a SIN based customer) when I asked if I could pay with a different credit card (not ANZ). Only thing being that they had to charge in HKD, which I was fine with.
This was the normal reservations line - not the MPC line for DMs. All sorted in a 14min call, including hold times.
Willing to bet the bottom dollar that a similar thing with SQ would have been unsolvable.
Point of the long story being that, CX has a definite "get it done" attitude, wheras SQ's is a lot more "I need to check the rules", "Oh, but we cant do that" or more likely "Sorry Canno" .
Myself, and I recall that KACommuter too have had a fair few frustrating experiences with SQ - be it standing by on earlier flights, or asking for something out of the box in case of irrops.
South Asian descent folks would know the word 'jugaad' - akin to a 'hack'. Perhaps its a HKG vs SIN thing, but CX's DNA is much better in getting things done in my experience.