Poor support service

Hi<br> <br> I sent my Sony Z3 for repairs for a cracked screen on 26/04/15, job number ***5. The phone was ready to be collected on the 24th of February. I collected the phone, paid R750 for the insurance excess. When I got home the phone would not read the sim card. I took the phone back and it was again booked in for repairs. About a week later I collected the phone and I was told that no fault was found. I tested it before I even left the store and it gave me the same error. It was booked in yet again. The new job number was ***2. The phone came back with a cracked screen and I'm told that it is a write off. When I ask the store assistant what I should do I'm should contact head office and offered no assistance beyond that. Not even the manager has offered an explanation for this awful service.I have to take upon myself to solve this yet we go to your stores for support