Hi @Arbaz1,
You may try searching online (Google, Firefox) and enter your street address and suburb in order to find out what your postcode is.
I recommend that you reset your account password by following the steps from this article:
Forgot your TPG account password?
Should you require further assistance, you may reach out to us again or you may check out our self-help options located here: http://tpg.com.au/support
Regards,
Ahra_G
