Caller: They said they were from Telstra

I've been having problem with my Telstra/NBN. This person has rung me twice from a NSW number and now a Vic number. Said he was in India. Was very aggressive and loud. Wanted to know what devices I was using at home exactly. Also told me if the problem wasn't sorted they would cut off my internet. I tried to speak several times but he talked over me. I told him I didn't like his attitude and I was terminating the call. If it is Telstra, then they need to remedy this process. Getting calls from random numbers and rude staff doesn't work