Want to return item

I took a phone contract on the 5th of April. The person who helped me didn't state the terms and conditions to me. Only stated that I had to pay double in the end of May. The phone I took there had no sample to show how it looked or what features it may have.. I feel this phone is not what I want and it is costly. I went in store to ask for my contract papers that I had signed. They said they can't give it to me. I was utterly mean until they had to print out 2 pages for me. I phoned the customer care line to state that I do Not want the phone and they said my "7 days grace period" is over and that cancelation fees would be R800.. The phone would be another R4500 and I had to pay additional more for the data I have used. Honestly I am not happy with the device and to pay all that for something I don't want is not right. I read that in the CPA law the customer has the right to return the goods/phone in 20 business working days. Yet the customer care people says they never hear of this law before. I am willing to pay for the cancelation fee and what data iv used but not for the phone and the contract. Please advice me. As I no longer want to be paying for something I do not need.