Apartment Property Manager won't fix mismatched system. New R410 condensor, old R22 indoor coil.

A few months ago we complained that our AC was running poorly. Their usual HVAC contractor came out and told us that the 1989 Rheem 1.8 Ton heat pump / condenser was worn out and needed to be replaced. A couple of weeks later, we have a new condenser on the roof, a 1.5 Ton Goodman heat pump / condenser.

The system is now performing worse than before. The apartment is humid when the AC runs, and the temperature diff between return and register is about 7°F. Somehow the property manager thinks this is OK and tells me "it's been hot in your area" and "it must be your finicky thermostat." We live in Los Angeles, not Florida.

So I hired an independent HVAC technician to inspect the equipment. He confirmed what I had suspected: that the indoor coil was supposed to be replaced at the same time as the roof unit. The old R22 unit is not getting saturated and can't pull enough heat out of the apartment.

He wrote up an estimate for $3,400. It seems awfully high for a part that wholesales for about $600 new, but whatever.

My wife took the invoice to the property management office and met with the owner. She seemed quite convinced that the two pieces can be changed separately, despite not being certified in anything except pushing papers.

The guy we hired said that the compressor will fail in 2-3 years because of the mismatched oils and refrigerants.

Is there anything we can do?

edit: pictures + manifold readings: http://imgur.com/a/mWPRb