Irrepairable phone

So I took my iPhone 5s for a repair when I was in Cape Town for a jazz festival end of March 2015.It had a water damage which made the phone to dial my contacts without my knowledge(the voice control function) otherwise it was working perfectly.They didn't send the msg about the quote,when I went back to check on the phone I didn't have enough time to wait for the phone to be fixed.So I took it with me to my surprise it was no longer working.When I charged it,it showed a red screen.When they sent a msg for me to rate their service,I indicated that my phone is no longer working.But thought I'll take it to Joburg.When I took it to Melrose arch(end July) they quoted me and I told them to go ahead and fix it.On the day of collection they told me my phone is irreparable...