Caller: Claims to be Telstra

Claimed to be Telstra calling about my internet. I requested their ABN and she wouldn’t give it. I said if you are Telstra put everything in an email and send it to me as you will have all my contact details. She said no. She could only give me the phone number for a helpline. I said no, I can find that info myself online. I’m alert to scams so if you’re a legitimate call you will provide your ABN and send me an email. She told me that’s fine I will cut off your internet and hung up.