vodacom / repairs / sony xperia m2 aqa

I have a contract with Vodacom. I upgrade about 3-4 months ago to a sony xperia m2 aqa. From the 29th of May up until the 26th of June (period of less than 1 month) I have booked the phone in 3 times for repairs. The 1st time it was in for repairs (just switching off and can't get it to switch back on) I had it back for 1 week and it went back for exactly the same problem. The 2nd time it got it back I had it for 3 days and it went back for repairs. It is at the advanced repairs centre for a 3rd time now within that 1 month period. Surely there is a problem with this model phone and it should be taken off the market instead of sending everyone's phones in for repairs all the time. My current job number for ref is ***7 (currently at repair centre) My son's phone (also at Vodacom) exactly the same model phone is also being taken back today for the 2nd time in 2 weeks with exactly the same problem. Hellloooooooo!!!!!! Something must be wrong with these phones. Thankyou. Anita Swart ( I demand a replacement of another model phone) please contact me on ***.