Be careful when upgrading with vodacom

I have been a loyal customer for over 20 years. My contract expired mid last year and I was contacted by the upgrades department to renew my contract. I initially had declined to renew it but felt the saleswoman sorry and said it's fine she may upgrade my contract to the EXACT same plan that I previously had. She agreed and upgraded both my lines. A few days later I was surprised to receive a modem via courier. I called vodacom only to be informed that the saleswoman actually upgraded my contract and added additional stuff to my contract with additional charges. I have been trying to resolve this issue for a few months and get transferred from 1 department to the next with no results. Can someone please help me