Default Repair options: broken headphone jack

I have 6833 sony ultra z. The headphone jack was always super-sensitive, recently it completely stopped detecting headphones. I sent it back for service and they refused to repair my phone
Apparently unlocking bootloader + flashing sony firmware is grounds for them to ignore mechanical failure problems. I sent the phone back with a locked bootloader, but I think I might've installed european sony firmware on it by accident ;(

Anyway, dont expect Sony to be reasonable with warranty unless you are super-sneaky with firmware flashing

Any suggestions on where to get the phone repaired?