Phone that can't last the term of the contract

I have a Sony Z1 which is on contract from March 2014, the phone has been in for repairs 3 times already and always comes back as software problem, how many times does the software need to be upgraded by Sony in a 24 month contract, every time it goes in its 2weeks with out a phone this is frustrating, now the phone software has been updated again and no fault found. This is ******** Vodacom must replace this phone, they are just trying to buy time for my contract to expire so they don't have to replace this **** phone , I cannot continue paying for a phone that doesn't work properly, I gave you guys a chance to fix it now I want a new phone for the balance of the duration of my contract.