Vodacom store at mall of Africa

I opened an with vodacom at mall of Africa sometime early this year. Called the store at mall of Africa first for exchanging the phone because it was complicated for an I phone 6...abd cost as well. With downloading apple app I called them within 7 days but they said to me its not allowed but when I check terms and conditions its not specified that its no allowed to exchange. Store manager from mall of Africa said its under my name so they can't do take and u already used and I only had it for a day. Wanted an cancelation fee, no help either. I believe when we as client come in vodacom store you must even inform us that as an contract client I have to pay extra month for caller ID. And pay for installing apple account I'm charged per 30 minutes. Likely I-store did it for and for free... I wanna cancel this contract.