vodacom refuses to cancel my contract

I have taken up a new contract on saturday 28 March 2015. Took the phone home. I did not even insert the sim card in the phone yet and took the phone back on Sunday 29 March with the phone brand new. The store refused to take back the phone as they say they did not force me to take the phone it was my choice. Yes I chose the phone however im not happy with the phone. Vodacoms policy is if you not happy with the phone you then have 14 days to cancel the contract. I took the phone back within a day and they refuse to cancel the contract. This is terrible service from vodacom and the store. Centurion mall vodacom. Im with vodacom 9 Years now this is the first time im having such trouble with them. So for me this is bad from vodacom.