Quote to expand existing solar system - Add another system

I have been contacted by a company called “ISOLUX” who are offering to add 7 Risen 330 panels and a "GROWATT 2 Kw Inverter for $3800. Can I please have your thoughts on this.
The old panels are 7 years old.

Hi Ron, it sounds very expensive for 7 ‘cheap’ panels and a very cheap inverter.

What is wrong with your current solar system? Is it just undersized or not performing as expected?

Thanks Svarky, There is nothing wrong with my current system which consists of 12 Trina panels (TSM-2500) and a 3kW SMA Sunnyboy (SB4000) installed at the end of 2012 by Blue Mountains Solar. I just wanted to add more panels. Do you know anything about ISOLUX as a company?

I have never heard of ISOLUX but based on the quote I get a bad ‘vibe’. It seems overpriced for very cheap panels and inverter. Is the roof steep, difficult to access or 2 storey?

I would definitely look around and get some more quotes.