VITO inverter useless

In May 2023 guys that install invetors came to my house and installed VITO inverter. It worked for a few months but it had noise and it worked non stop. It has stop working after we had load shedding. I have not even finished paying the bank but VITO inverter is not working. I was told not to use anything when it's working and I followed those instructions. I don't even know where to take it