Being pushed pillar to post with no resolution

A few months ago I took out a contract for a Samsung s4 due to a fault I returned the device within the 7 days grace period advised the faults agent took phone they booked the phone in and proved that it is faulty . I wrote to hello peter and telkom responded within 2 hours then said would call back in 72 hours to resolve the issue I waited for a month still no call back went into store to see the manager been promising to give me feed back ive been going in to store regularly for a follow up but no conclusion is given but my account is being debited on a monthly basis for a phone I don't have only had for 5 days and it's 5 months later still paying for a device which was faulty and they didn't have stock for a exchange so requested to cancel because the other phone I wanted wasn't available . I gave the manager an alternative resolution requested I get an iPhone 6 at a discounted rate due to the inconvenience caused but that was declined i always get pushed pillar to post and I use my money for parking to be told I will call you when I get a response which never happens in 6 month only call I got was after writing into hellopeter and nothing after service is terrible please help