My own view is that it's worth trying to get these issues fixed. I have a suspicion that the aircon thing may just be the way the MG4's aircon works, and I've certainly found it to be absolutely fine once I understand that the temperature the car shows me is about 5 degrees higher than the temperature it is giving me, and that whether the aircon is on or off is entirely under my control. I like the HVAC system, I find it's giving me a nice comfortable temperature in the car without blasting me with hot or cold air.
If you fiddle with the system, and in particular fiddle with what happens at a given temperature with the AC turned on versus with it turned off (given that the car, as far as I know, slavishly obeys the driver as to whether it's on or off), you might find that it's just as good for you.
Your problems with the satnav and the screen freezing are real problems I think, but they're not in the same league as the horrors Bowfer and others experienced with the power/speed limitation, and I would have thought they should be relatively easy to fix.
Tell the dealer to bloody well sort it or you'll hand the car back?