I have exactly the same problem that started about the same time as yours. I checked this community page and see that many people have been complaining about not being able to make international calls - China, USA, Brazil, Russia (my case). And everybody gives exactly the same timeframe as when it started happening to me (from this Aug). Have they solved your issue?
Welcome to the community! My apologies for the ongoing issues with your mobile service wherein you cannot make international calls to Russia. I've managed to check your account records and it shows here that we've made routing changes for your service, however, it looks like the changes didn't fix the issue. Our mobile escalation team has organised a SIM card replacement last 24/October/2018 on your request. The SIM card has been shipped via Australia post Thursday last week. Once shipped, it usually takes 2-5 working days to be delivered. Once you have the new SIM card and you need assistance in activation you will find this community article helpful: How to activate your TPG mobile SIM this will guide you in the activation process. Please test your outgoing international call as soon as your new SIM card becomes active and let us know should you need further contact for assistance.
Thanks to getting back to me. As I've already mentioned in my post, I got the new sim card today and already activated it. More than 2,5 hours passed since activation. It didn't fix anything. I AM STILL NOT ABLE TO MAKE INTERNATIONAL PHONE CALLS TO ,OBILE NUMBERS IN RUSSIA!!!
I understand that our Mobile team has been in touch and the case was lodged to our Network engineers for further investigation. We apologise for the inconvenience that this has caused as our team can't detect the fault on the network.
Further updates will be given once available. The request for compensation will be assessed once the case is resolved.
Thank you for your patience.