Shouldn't have to replace the aircon/heat-pump components, only the controller hardware. OP indicated that a new control system would be about $1700 (I assume AUD), or 14-17% of their 10k-12k estimate for the whole build.
Unless this scummy manufacturer also works with the aircon makers to lock those to their controllers. (That would be a great lawsuit to watch.)
Unless this scummy manufacturer also works with the aircon makers to lock those to their controllers. (That would be a great lawsuit to watch.)