Incapable of honouring an agree contract

I have had nothing but appalling dealings with Vodacom Fibre since December 2023 when I received notification that I was being "upgraded" to 50/50 whether I liked it or not. I contacted them to cancel my fibre as I was going to switch to Supersonic for R599 (inclusive) for the 20/20 line and it was Vodacom that offered me to continue with my 20/20 at the price of R599 in order to remain as one of their clients. This was agreed. Since then it has been a billing nightmare. For the last three months I was billed for two fibre lines (50/50 + 20/20 at Vodacom prices which are much higher than Supersonic). Every month I phone and they can see the agreed price of R599 (inclusive), every month they escalate and every month the bill is totally incorrect. This month I get an invoice for a 50/50 line plus an additional R125 totaling R992.75 and again have to phone. Again an escalation! I am at my wits end with this company, they are totally incapable implementing a negotiated contract never mind solving any billing queries. On top of everything else you can't hear a thing as the call centre sounds like a loud, shouting match from all the call centre agents speaking at the top of their voices. I can't wait for this contract to end so that I can turn my back on the most useless company providing fibre. Appalling does not begin to describe the experience!