Poor service from Vodacom team

I was contacted at the end of September by a vodacom agent to do an upgrade. I accepted the upgrade but just after I put the phone down my son said the device i upgraded for was not the best and I shouldn't take it. I called back shortly there after and spoke to a consultant who assured me that they will reverse the deal and cancel the upgrade request. The cancelation was done but yet the device was delivered to me. I had called on numerous occasions to have the device collected which was eventually done but I am still being billed +/- R2000 for the device that I don't have. I have called vodacom on numerous occasions and they keep telling me that the reversal is done yet my invoice is still showing me the amount for the device. I have multiple reference numbers and contact names I have spoken to. Reference numbers are as follows: Rebecca RCO 146245, Nontlhe - ***, Tume - ***1D6028B8, Nomfundo Mabaso, Ramusa, Ruth, Tshepo- ***, Nandi-***, Dieketseng - ***, Yvonne ***, Mondeor department - Acona -1-CGVCLS8T, Tshgofatso - ***1st December, Prudence- ***, and lastly Oleweto whom I advise that I will be contacting Hello Peter.