System does not conform to requirements

I bought a solar energy system from Geoty on 17/01/2022. Firstly their approved installer did a very poor installation. They had no idea of any installation recommendations and used totally wrong wiring to the inverter. Secondly, the system was specified to supply 9 kWh per day. I hardly get 6 kWh per day, average is about 5.5 kWh per day. I left numerous phone messages and even went their twice to complain but they do not assist and do not call back. I hold them responsible to fix the system or replace it to achieve the specified energy. I'm very disappointed and will never recommend them to prospective buyers.