Poor Customer Service

I bought a phone in Vodacom at Festival Mall Shop no.8(Entrance 1) in October 2014. I went home and I did a mistake of throwing away the box. I was 9 months pregnant at the time of buying the phone I had to go to the hospital and when I came back that's when I put a Sim card only to find out the phone could not take the Vodacom Sim card but when you put another network like Cell C its working. I took the phone back to the shop and they said they want the box and I have already threw it away because I never thought the phone is not working since I have used Vodacom for so long and never experienced any problem. The Store Manager said he cannot return the phone to Vodacom he will take the phone to Vodacom spares. They said the phone its been damaged I must pay R800. I payed R800 because I did not want to ague. I never ever used the phone I did not even make a call because it does not take Vodacom network. My phone is still with spares in Vodacom and the Manager of the store in Festival Mall does not care and he does not even follow up with spares. When I bought the phone he never checked if its working by putting a Sim card to show me that it is working he just gave me a phone.