Vodacom contract phone

I had a 12 months contract with Vodacom from 02/2020 and they provided me with such good service. From the insurance because my phone fell and died adult some point to the day to day services. In Jan 2021 when I was due for an upgrade I decided to continue with the service provider and ordered an upgrade online with them. I realized when I received my device that it was a pre loved device and I wanted a new device. That was my fault because I did not know what a pre loved device was. I then called vodacom on the same day I received the device to let them know that I am not happy with it and would like to return the device. A few days later the device was collected and all was in order. I then called them to cancel the contract as I had seen a better deal on another service provider and I was informed that they have not received the device so I’d have to wait till they receive and inspect the device and that this will probably take a week to ten days. Mind you we are not in feb and the contract is still not cancelled. Ten days later I call again and they inform me that the device was received and all is in order so I request to close the account and the lady assisting me does that and I assume all is well. About a month or two letter I received a call and I am informed that I owe Vodacom for my contract, I explain to this person on the line that the contract was closed and she say well no it is not closed and that is because you tried to close in Feb when you were owing us already. I then say to her, I understand I made the mistake and all. I inform her that I will pay for the month which was about R500. She says that since the account has been active it has accumulated interest and I will have to pay the whole amount! Now that’s where my problem is, the lady I spoke to when I was closing my contract initially should told me this and I was definitely going to pay it immediately. She failed to do her job and now I should suffer. I told this Second Lady that will only pay the R500 I owe but before I do that they must send me a tax invoice with the correct amount which is R500. She say I must pay the R500 then they will deal with the remaining. Now how can I trust these people who are failing me at this point. I try to call back on a different and I am passed around like a mad person. I even tried going to Vodacom the glen and I was told that they can’t assist me because this was done online initially. Now my thing is these people say their calls are recorded but they fail to go back and listen to our first conversation? The amount is now at R2000 or something and VVM keeps calling and I keep telling them the same thing and sending emails. I am honestly tired! I even I want to change my primary number at this point.