Ha! They did the same thing to me...
3 calls, hours of "troubleshooting", and tests performed by the "engineer" team, and they tell me it's because my tpg router is faulty, but "unfortunately" it would cost money to get a new router from them OR I could lock myself in for another 2 years to get a free one...
I asked them if they have a router I can buy that has the functionality I need, and they didn't, but recommended I buy a third party one that is nbn ready.
So i did. I went out and bought one, set it up for the internet expecting it to have solved the problem, and... Nope... Same problem still...
I call back, and they now tell me they won't provide customer support if I don't have their modem plugged in... But they told me it was faulty... That it's garbage.... I don't have it anymore because I threw out the router when I bought a new one, and seeing as they said it's faulty, it's not like there's any reason to keep it...
So now I'm at the same situation, where they are probably gonna expect me to purchase a new tpg brand modem to be able to get a technician out to my address. Which they know is the next step, but strangely can't do that without having their modem plugged in.
A mod here has said they've escelated it at least, but honestly if I don't get a call before the end of the day, and get a technician appointment set up, I'm just gonna walk into a telstra shop and switch providers.