We recommend having a read of these community articles, which may help with your concern:
I've managed to locate your account using your Community details and have seen that there is an active call forwarding.
Customers can enable or disable this feature anytime via their TPG online account. (My Account)
Customer may also request this by calling TPG Customer Service Hotline 13 14 23 Option 3 + 1
If the issue persists, let us know your most convenient time to receive a call for our Technical team to assist you.