Terrible customer service!

I got the Sony Experia Z1 Compact October 2014. In January the phone was in water the first time after checking several times all covers were properly closed. No deeper than 30cm in fresh water and no longer than about 5 seconds at a time.(Claims to be water proof up to 1,5m and up to 30minutes) I noticed moisture in the camera lens and later when phone was completely dry opened covers and there was water in every opening. The phone would not charge anymore and I took it in for repairs to Vodacom. After about 3 weeks it came back with report it was not fixed due to water damage and a hairline crack!? The phone must have been a dud as it never fell or was knocked! I feel if I pay in on my contract for a phone with specific specs it should live up to it or be replaced. I refuse to pay in on my contract any longer for a almost R10000 phone I used for less than 3 months without me doing anything the phone was not suppose to be able to do! My next step is cancelling my contract with Vodacom after years of being on this network and going to a network that will actually follow up on problems and not just give me back a useless phone. I really hope it does not have to go that way.