Dissappinted

I upgraded my contract and got the new samsung galaxy s 6, within the first 6 days the fone froze 3 times for a period of 10 minutes, i gave it in on the 28 th of april, they said they would send the phone in and that i would have an answer by monday, monday came and gone. It is friday a week after i gave the phobe in, and today they said that nothing is wrong with the phone and thier sending it back and i will have it back next week, 2 weeks after i gave it in, second there is something wrong with the phone And i dont want that phone back if it is giving problems, within the first week if there is something wrong with the phone they should replace it, now they are sending me the same phone back, i am verry disappointed in vodacom, and i think this is unacceptable.