Misleading/poor service

I have been with Vodacom since 1998. I was due for an upgrade in 2017 but choose to retain my device as it was still in good working order. My monthly fee was subsequently reduced. Earlier this year I was contacted by a Vodacom representative who indicated that they could offer me a "better" monthly fee. I agreed to this. But, the monthly fee actually increased. Furthermore, I recently decided that I needed to upgrade my device, but the automated Vodacom system indicated that I can only upgrade in 2020. I called the call centre on 31 July to report this matter and indicate that I had been mislead by a Vodacom representative. I was informed that I would be contacted within 48 hours. I am still waiting for a response (despite a follow-up call).