Sony Z5 Xperia Repair

I bought my cellphone (Sony Xperia Z5) on contract with Vodacom, my phone fell and the screen cracked then i took it for repairs in Vodacom Repair Center since i have a contract with them, they replaced the screen and still i wasn't satisfied with the repairs the took it back (THEY EVEN TOLD ME THAT THE PHONE IS GOING TO LOOSE WARRANTY BEFORE THEY REPLACED THE SCREEN) . After a week i called to find out how far are they with my phone and the response was that my phone is irreparable and some of the components are missing and its not their fault. they damaged my phone even more and now because they cant fix it they want to give it back with missing components and i am still paying the phone.