Caller: Supposedly someone from Telstra

Caller had an accent claimed to be calling from Telstra to improve our Internet speed as it was slowing. Told him I don't get it ( just playing along to get their spiel ) - proceeded to call me a f*cking idiot so hung up

Obviously, a scam as this is about the third such call I have had in a month..you can hear the call centre noise in the background of other calls being made, plus there is a delay in the call being connected once you answer.