Hi @limyongpeng,
It appears that this is not an Australian number.
TPG Australia & TPG Singapore are 2 separate entities.
Kindly send an email to Singapore Mobile Team at support@tpgmobile.com.sg so they can provide further assistance.
You may also reach out to their social media pages:
Instagram: https://www.instagram.com/tpgsingapore
Facebook: https://www.facebook.com/tpgmobilesg/
Cheers!
