Sony Xperia

Today is the 4th time that I will need to take my Sony Xperia to Vodacom repairs. This time the screen has just froze and I am unable to do anything with it. and it is not even a week since I received it back from the last repair. Following my last complaint I received feedback from Sony saying that my complaint has been escalated and I must be patient. Well SONY my patience has now RUN OUT!!!. Not only am I being totally inconvenienced by a phone that isn't working I loose all my information on my phone every time I take it in. How many times do I have to take my phone in for repairs before I can receive a new handset. surely it is obvious that this phone is faulty. Who has my precious complaint been escalated too and WHAT are you going to do this time? Lip service me again.. What are my rights as a customer? Seriously I'm done!!