3 months to relpace phone under warranty

My I-Phone (purchased in July 2015)has been with MTN since the 27th December, to say progress is slow is an understatement. Fist they call me back in Jan to tell me to take off the look for my I-phone and charged me R350 for the pleasure. Why could they not have told me to do this when I handed it in in the first place!! I was then told that they would replace the phone which is great! You would think ..... They have no stock ... I asked for the branch to replace it .. cant be done ,, BECAUSE they give you a refurbished phone .... I took a contract for a NEW I-Phone I don't know why now I have to pay full price for a refurbished phone . ALSO pay for 3 months of Data that I can't use because they have my phone.... Oh and try to speak to someone in authority at MTN ... That's a joke . Surely if you replace under warranty it's with a new phone, and in a week? I am so angry this is beyond acceptable.