Frustrated Vodacom Customer

I am so frustrated with Vodacom. I have again been billed the incorrect amount. This has been ongoing for the past 4 months. I don't know how many people I have spoken to me that keep calling me about my contract and upgrading it's as if your systems don't speak to each other or don't get updated. I thought it was finally resolved when I was then billed the correct amount - although never refunded for the incorrectly billed amounts. Now my contract has gone from R372.84 to R556.54 in one month. At this point, I think I just need to exit this relationship. I can't keep spending hours on the phone only for the incorrect actions to be taken and my account be billed incorrectly.