Debiting for a device which was returned

I received a telemarketing call in February 2014 from One Life, offering me a Vodacom contract, which I was bul**** into accepting. Couriers delivered a Samsung Pocket cellphone to me in Bela Belal in February. I told the courier representative that I no longer wanted the phone and he said I should take it and then return it to Vodacom. I called the Vodacom help line in February 2014, and the agent advised that they will collect the Samsung cell phone, which had not been opened, within 4 days, which they did. The same couriers collected the phone. Vodacom started to debit my account in March 2014, and continued to do so for 8 months until I closed it. I started receiving threatening sms's from attorneys Burnard and Raaff. at the beginning of November 2015. I called them and as per their request I submitted an affedavit on 13 November 2015. Vodacom has deducted R800 from my account for a device that I never wanted, never used, and returned. I want to be refunded, and have the case closed.