Charged incorrect account fees

Been complaining about my mtn account for the last 3 months without a resolution. Been speaking with a few of agents but they was no resolution of the matter. Called in again on Monday and was assisted by a lovely lady Takalani and she promised to escalate my query which she did and asked me to call in again after 5-7 days Called in again today then I spoke to Kara o which she was trying her best to assist and then asked to be transferred to a manager named Ndumiso. I have never dealt with a such unprofessional, unsympathetic manager ever in my life. He didn't want to list to my query but kept on saying we can't assist you with what you wants us to. There have Breen ***** on my contract simcard and they told me they don't have a ***** department to sendy request. I have bee in billed. R1400 for calls that I HAVE NEVER MADE BIT THYE FORCING ME THAT I USED THE SIMCARD. Kindly asked them to investigate which phone and IMEI number of the device that made the outbound calls and I was told that's not possible and can't be assisted. I told this damn manager that I won't pay for the charges because I have never made the calls out. I explained when I took the contract I wanted the device hence I destroyed the simcard long time ago but I can't be heard all I get is that I have to pay for something I have never used. That's unacceptable and uncalled for to be treated like that as a service provider they have to protect their clients whenever there's ***** that happens. I'm so done with MTN and want to close my account and go somewhere were I will be treated fairly well as a client.