This is from Singtel Hi menu:
https://i.imgur.com/z6WmqYx.png
Notice it says "Data plans" - They give you only data and claim to give you free incoming only for 20 days as a bonus. That's not even a bonus, in India, you pay nothing for incoming, at least on the Airtel plan I mentioned.
Also, about your point on being expensive - Singtel is the only Telco that doesn't suck in terms of network coverage in the country. Starhub is a close second, with slightly cheaper plans depending on what you're after and M1 is garbage and everyone knows that.
I suggest you try 4G somewhere near Toa Payoh, Bishan, Bedok or even some places within Paya Lebar.
Not sure why you had to be so rude (5 minutes of research?) and created a new account just to contest this..oh well.