Contact centre agents are completely unable to book anything other than codeshares on "royal jets" i.e. KLM
No possibility for them to book SQ or CX.
Asked for a supervisor and was told that they all go home at 5pm CGK time.

I was told to try going to LHR T3 to rebook - not a real ticket desk and not operational on non-flight days
Then I was told to call into the Jakarta ticket office in person... I explained that this was rather difficult given that they've just cancelled the flight to CGK from London, where I'm currently located.

The UK contact number is down at the moment but people who have managed to get through have been told by UK staff that only Jakarta can make changes to web bookings. Jakarta are telling us only UK can make changes...

Finally after about an hour on the phone the agent told me that there was some new information. Apparently the team leader hadn't gone home and instead had been in a meeting to discuss the situation with the LHR flights. There will be another meeting tomorrow to finalise things and then apparently we'll know for sure what's going on.

I'm not holding my breath