No way to complain about the system error. No AFCA regulation

Trading status: April 21, 2020
I wanna trade via ThinkTrader App
I traded at about 16:40 and it went smoothly which can verify that my phone and the network are normal.
I invested 250 positions of WTI Oil and I decided to close positions at 17:05. And when I was closing the positions, the network slagged. And I checked my positions after I had executed and the system showed that there was no position. So I thought that I closed all positions at that time
After that, I checked the system again and found that I finished transactions at 17:11 cuz the margin was insufficient. But I didn’t know that. So the broker should compensate me. But =111 refused
Share my experience:
They didn’t answer me until 15 days passed. I complained this broker to AFCA while they don’t have the right to regulate this broker. Because Thinkmarkets said my account belonged to them. But the email sent by them hasn’t mentioned Think Capital Limited and their official email said the financial products were offered by TF Global Markets (UK) Ltdor TF Global Markets (Aust) Pty Ltd
I hope investors who have the same experience as me could hep me handle the issue. Thanks.