CONTRACT TO BE CANCELLED - POOR SERVICE

I took an Iphone 4s on contract 11/9/15 from MTN the Glen.On 23/10/15 the phone was handed in at Simmonds Str for repairs.I called the repair centre a number of times as the ph was not returned and the assesment was not done as the phone was \still active\".No call was recd from them.MTN The Glen de activated the acc.I made payment ZAR 330.00 before the technician could check the phone.I called on 17/12/15 and was told that a replacement was to be sent .I refused as my phone was brand new with plastic on both sides, and no applications were loaded.I requested to speak to the manager,as I did not want someone else's repaired phone.Sarah Naidoo adv me that the phone would be sent to the walkin centre in Midrand for a warranty assesment.I was told to see Suyash/ Kushul.I went to Midrand 29/12/15,Kushul notified me that a replacement was on its way back to Simm Str.They were closed until 5/1/16.WHY AM I AS THE PAYING CUSTOMER BEING SENT ON A RUN.I did not accept the phone as a refurbished phone was sent.I called Sarah and told her that i wanted my own unit.How many more times must I call?? and wait.I am expected to pay my contract for the 2 year.CANCEL CONTRACT."