Unhappy customer. I am going to cancel my contract

Hi. My fiance has upgraded her current contract and has chosen the sony z3 compact. she currently has a samsung s3 so a swim swop is required for her to use her new phone. We did the swim swop at the branch where we got the new phone and were told to wait 24hrs for it to be activated. we had waited approximately 2 weeks for the sim to be activated and each day we phoned the branch many times as well as the very unhelpful call centre to sort out this problem. We eventually found out that the new sim card was under someone elses name and had to do a new swim swop on Tuesday 27 March 2015. we were told to wait yet another 24 hrs and the sim will be ready. We have done so and still no response. we have phoned the call centre yet again on the 26th March 2015 and were told to wait approximately 2 hrs and it will be sorted. the sim card is inactive and it doesnt allow incoming or outgoing calls. I am really disappointed with the service and i am going to cancel my contract if this matter is not treated urgently. I am aware that inorder to cancel the contract, i have to pay the remaining months of the contract. I will refuse to do this and will raise this matter with higher authority.