Heya a sub brand of Singtel has silently launched a SIM ONLY DATA plan at S$8 per 30 days. It comes with 150 GB of bundled data and 8 GB of roaming data.
During this promotion period, the plan offers 40GB of data which can be
used in Malaysia, Indonesia or Thailand. All data can be rolled over.

The plan can only be signed up at selected heya retail outlets as follows :
Liang Heng Clock and Watches
No. 31 Marina Coastal Drive #01-06 Marina South Pier
Hi-Tech Service (S) Pte Ltd
672 Chander Road, #01-42
YG PHONECARD
1 Maritime Sq Kiosk 1 Harbourfront Centre #01-15
SMS Mobiles
98 SYED ALWI ROAD
11-8 MART
30 WOODLANDS AVENUE 2 #01-46 WOODLANDS MRT STATION
Kranji Mobile
960 Woodlands Rd #01-11 Kranji MRT