Vodacom not resolving my problem

I upgraded my phone last year May 2017. I was hoping to pay a smaller amount to help me and my baby, so I chose a smaller package. To my surprise, I paid more than a thousand rand each month! The smaller package is more or less R410.00 When I queried this, they told me that I upgraded too soon and I need to pay for my old package until such time that my contract expired with the old one. I accepted this explanation, as I am not an unreasonable person. It is now FEB 2018 and I am still paying for a second handset!!! Vodacom did a recon in the beginning of Jan 2018 and discovered that they now owe me Credit. Needless to say, I am STILL waiting for the credit to be paid into my bank account. They keep on saying 7 to 14 working days etc. When I went onto my Vodacom account for FEB2018 I saw that the second hand set it STILL on my account. On the 5th of Feb 2018 I sent my last E-mail asking for proper feedback either via mail or phone. Seems as if they are now ignoring my E-mails