Bad service

Im Gloria from Thembisa. I have a contract with Cellc. I made an upgrade and has delivered on the 29Sept2015. It happened that the phn was faulty on 02/10/15 and i phoned them and they gave me OBF nr and promised to come collect it. Suddenly on the 06 before collection the phn was OK and I phoned 2 cancel. Apparently on 08 Oct phn started again de same problem & I phoned them again & spoke to Anelisa & she gave me OBF nr that they will collect it. No 1 came till I made a follow up & spoke 2 Tumie who told me that no call has been made by Anelisa and she told me she's gonna book it 4 repairs & I refused that because that's Anelisa's fault I need a new phn coz i used the phone less than 5 days it's still have a plastic. She kept quiet & decided 2give me a ref by an SMS. I've made a follow up till today with no help and the phone is still with me. If they can take this new phone to repair 1 problem what if there's another 1 to be descovered later, am I have to pay a reject phone for a normal price? I need a new phone because I booked the phone in time and I kept it nicely for them to see that I used it less than 5 days