Samsung — PC02 error in my samsung AC

I purchased samsung inverter AC 2yrs ago. During the installation, samsung technician told that it's in-built stabilizer and no need for external voltage stabilizer.
With limited usage, now I m getting PC02 error. Raised a complaint with Samsung and technician came and told that PCB board would have gone due to voltage fluctuations and need to be replaced. He also asked why there is no external voltage stabilizer? I was surprised as the initial technician told it's not required. I am given a quotation of 7k for this PCB board replacement (as it's out of warranty)
Now due to wrong guidance from samsung technician, I have to pay 7k and anyways hav to go for stabilizer. This is very poor service from Samsung.