Vodacom Contract

I am not happy with Vodacom. They extended my contract without my knowledge 17 April 2021. The agent who called me said they were reducing my premium to R179 from R298 and I asked if that won't change my contract and they said No. 23 June 2020 I discovered that they have upgraded. I've been calling them since then for them to cancel but they don't cancel. They send me from pillar to post.