iPhone 4 S Searchig for Network

i purchased a vodacom contract from cellucity which came with an iphone 4s in July 2014. In december 2014 it started saying searching for network and couldnt be used. this was verified by cellucity manager Fuad and cellucity staff as well as viodacom staff.we were told that the phone needed to be booked in, we asked that they not repair it rather give us feedback.through numerous calls and emails and meeting we were told our phone wasnt broken but infact working. which was strange and which meant everyone that saw the phone was wrong.we accepted the phone back as Malcom didnt want to acknowledge our right as stated by the cpa to cancel the contract. we had to book the phone in on the 18.04.15 for the same problem.Malcom said we would get a brand new replacement on 21.04.15, he didnt call me back i called him on the 22.04.15 he wasnt available then i called him on the 24.04.15 not available, left a message, he called back said i will have a phone by 28.04.15. today is the 29.04.15 still no feedback from Malcom and no phone. i have all emails from 2014 and all reference numbers.