Because they obviously don't know anything about the heater core of the Z32. It can't possibly be "the hoses" like they said, because the metal tubes exiting the core go straight through the firewall and then attach to hoses, so if it were the hoses you'd have a leak in the engine bay, not the cabin. It's definitely the core, and you can do it yourself just use Search for a writeup and other tips.
- Ty Martin Thou shalt not place rear wheel on backwards