Vodacom - poor service

An I-phone 6 that I ordered (Oct / Nov 2017) on the Internet was returned to Vodacom as soon as I realized that it was not an upgrade as I intended it to be, but an additional contract. It was done within 2 days (they received the phone in time via their courier service provider). After 8 months they are still debiting my banking account for this contract after ignoring a telephonic report. A second telephonic complaint was brought om 17 July. Up to today (19 July) I haven't received any update from them. Their consultant (at subscriber collections) told me she is not authorised to provide an e-mail address for their after sales dept so that I could contact them. I was to be satisfied by her e-mail to them. I can not understand why they do not return the amount they owe me. JH Jordaan