This is the response from Teamviewer. They actually don't know how difficult this will be to get done..
Thanks for contacting us. We have heard from a number of users in South Africa yesterday and today, all of whom are customers of Telkom and who are having trouble connecting with TeamViewer. Our own technicians have investigated this and have confirmed that the issue lies with Telkom, not with TeamViewer. The problem only appears to exist when you are trying to make a connection to another Telkom user, but if you make a connection to a remote computer that is outside of Telkom's network, it will work fine.
Can you chase the matter up with Telkom again? Try to escalate it higher with them, eg. to their 2nd Level or 3rd Level Support team if you can.
Thanks, but we have an issue using Telkom LTE at home trying to connect to the office using IS bandwidth.