Treating customers badly when not interested in an upgrade.

Got a phone call from Vodacom, my one contract expires in October 2018. Advised her I am not interested in upgrading. She was talking so loud I had to hold the phone a few centimeters away from my ear. When I told her I am not interested she got aggressive and told I am not listening and I must stop screaming at her!!! I was not even raising my voice. This is not acceptable. Treating customers so badly.