Cancellation of contract

My name SJ MOLOBELA, Cell number ********** , I have two contract phones with Vodacom, A couple of weeks I got a call from Vodacom telling me about a new contract phone that they would like to offer me, it was a new sumsang TAB3 lite, It was not clearly explained as Iam having the similar phone at that moment. I decided to cancel the deal on the day of delivery and called them as Iam aware to cancel before end of 15 days. They said to me, the phone will be collected within 3 to 10 days, the phone was never collected till today and the installment of R179.00 was debited on my account on the 25th Sept 2017. I called them to inquire again and was told I never cancelled the deal and they cant collect the phone anymore because it is more than 15 days now, I don't need that phone and want my money back.