Unauthorized upgrade

My name is Nonkululeko Matsoso, I have 5 contracts with Vodacom, one of those contracted phones was due for an upgrade on the 31st July 2015 but I decided not to upgrade since my phone was still fine with I was, however, sometime in August Samukelisiwe from Vodacom called me to remind me about my upgrade and I told her that at that time I did not want to upgrade since I was still fine with my phone then she said to me, I quote, ' since you've been with Vodacom for such a long time Vodacom would like to thank you by giving you a phone and a tablet as a gift'. Although it was difficult to believe that I accepted and that was delivered to me. A month later when I decided to go for my upgrade I was told I can only upgrade in July 2017 then I asked the reason for that I was told that Samukelisiwe have processed my upgrade. I requested for this matter to be investigated then I was told return those gargerts that were delivered to me and I did that. Cheryl now is refusing to reverse my upgrade.