I've done all I can, calling them almost every single day except weekend, went down to Comcentre on Monday, waited almost 2 hrs and having the CSO there asking me to call back 1688 and providing EID of the watch in which the 1688 CSOs don't know about this. After that emailing the screenshot of my problem and finally got it to work 2 days after the email.
To summarise, from a stuck order, to cessation of numbershare (which I received confirmation) so I can re-subscribe which also resulted in becoming stuck again, then resolution of the stuck order (finally), then mobile service setting up via AW app still telling me I'm subscribed to numbershare, then wait again, then going down Comcentre, then email and finally able to re-subscribe just now and it's working.
Dunno what's wrong with Singtel now but after over 2 decades being with them, this case takes the cake for being the most problematic.