H Gap — Defective product

I had purchased a Solar invertor of H Gap. Which is still in warranty and has been repaired 8-9 times by vendor who installed the project.
But every-time it gets repaired, works for some time and later gets shut down.
For the setup in which this invertor is installed is not appropriate for this, and break down happens.
Once it even caught fire, which eventually spread out and entire material in that room caught fire and we got panic and called the vendor who again visited and took the invertor at his place for repair.
Which again break down after 4 days of replacement of that invertor at my place.
I am running a guest house and marriage garden where this invertor is placed and the party whose booking happens, gets irritated due to power breakdown and we result into miserable level of service.
We called one official of H Gap, but he listened to my issue and disconnected the call.

Now when it comes out of warranty, they will pull off their hand and till that time they are just giving temporary solution.

Here i need to replace this product by any other product which matches my set up capacity or may return my amount.