Actually if you state the issue properly, Singtel front staff is quite okay.
For my Singtel ONR IPv6 technical case, I use WhatsApp Singtel channel to contact Singtel. After the brief verification, I told the support guy the issue including screenshots and I also mentioned the following link to them.
https://forums.hardwarezone.com.sg/threads/singtel-5gbps-ipv6.7053976/
I told the support guy the issue is an advanced issue that needs the backend network team to be involved. He agreed and created the support case.
I am not saying the issue will be sorted out easily but at least the front end support guy is very good and not wasting my time.
All in all my interactions with Singtel support are alll positive. But this is the first time it is a real technical question. Previously I was using ONT and no need any technical support from Singtel.
Let's see how it goes this time with regard to ONR and Singtel IPv6.