Vodacom incorrectly bills me R12 863!!

Part 3: Sadly, the integrity and honesty of Vodacom further declines since the events that took place in December. The last conversation I had with Vodacom was on 1 February 2024, where Pinkie, Crystal, Jim and Dean called me to confirm that the matter is resolved and that the 2x Honor 90 phones were received and that my contract would revert back to the Flexi 140 plan that I had previously; and that R518 would be credited to me for the balance of the contract. Upon my shock, I've received an invoice and SMS this morning 19 March 2024, saying that I owe Vodacom R12 863.10. I have contacted Vodacom immediately and a Noluthando confirmed that "there is Equipment: Balance of Contract 15, which you are charged for". I cannot stress enough how in competent and un ethical this company is and I want urgent rectification of this.