When sending feedback to SQ via the web form, how long does it typically take to receive a response?

I submitted some feedback about our malfunctioning (consistently hanging/requiring crew reboots) KrisWorld units on a flight my wife and I took on December 6 (on the 77W in J), hoping for at least some acknowledgement from SQ. To date, I've heard nothing back--is that typical? Are there any alternate routes people recommend for getting a response? I can't find a customer service phone number anywhere on the website.

My only other data point was an email I sent to KrisFlyer customer service a day or two later, which received a response the next day. Should I not plan on getting any response from SQ on my prior letter?