Hi @kyawminthu ,
Welcome to the Community!
It appears that your service is under TPG Singapore.
For any concern you have with TPG Singapore you can send an email to Singapore Mobile Team at email@example.com or visit their Facebook Page at https://www.facebook.com/TPG-Singapore-785533401811953/ as this page is dedicated for TPG Australia customers.
Please be advised that TPG AU & TPG SG are 2 separate entities.