Sinetech de*****ed me

I've been de*****ed by Sinetech. I had to pay for an off-grid solar system upfront. Three weeks later they installed a completely different system that does not work. I paid for 2 x 275w solar panels, and they installed 2 x 200w panels. The system is faulty and does not work. They ignore my calls and do not respond to emails. I have been de*****ed!