Can't believe the dishonesty and horrible service...

I got a new cell phone 2 months ago from Vodacom, then about a month later the screen started "phantom typing", it's when the screen types on its own, and opens apps by itself, I contacted Sony, and they said I should take it to Vodacom. Got there they sent my phone away to be "repaired" when I got it back today I was told it is only a software problem, but the phone does exactly the same, the screen goes nuts as if a ghost is playing with it.