Bad service

In 2015 September I took a 24 months contract with Vodacom and last year in May I called the Call center and ask them to tell me how much was left on my contract because I wanted to settle my debt. The Consultants that I spoke to gave me different quotes but the last one said its R1200 and some odds. I then asked if I made that particular payment my account will be converted from contract to prepaid? the answer was yes. I then made the payment in question and then call the Call Center to cancel my contract and move it to prepaid as I have settled my account. The consultant told me they can not do that because my account was owing. I then requested to speak to someone higher than her and explained my story and I even requested them to listen to the call recording for that day and she heard everything. The lady who assisted me had told me that she will move my account from contract to prepaid but on their system it will take a while to update the information. It was June 2017 when my account had been converted from contract to prepaid and removed my outstanding debt. Now today 15th Jan 2018 I am receiving a call from the debt collectors to say I owe Vodacom an amount of R3042.95 which I know nothing about it. I tried calling their call center and Nqobile and Nkuli both informed that my account is on prepaid and nothing shows amount owing on their side and advised that I call the Legal Dept, which i did and automated machine just told me my account has been handed over to debt Collectors.

I need to speak to someone who can assist me with my query, I am real tired of Vodacom trying to mess my name around.I want vodacom to remove my name from this nonsense.

I will not take this lightly, as this will affect my credit score. why is Vodacom trying milk me like this? I so annoyed now with this behavior.