Poor service

I had my system installed in March 2021 . The geyser is faulty and does not heat up the water. I complained on their WhatsApp number a couple of times . I also called their offices just to be promised they will come back to me . when they eventually returned my call , they had the audacity to tell me that although my system is still under guarantee , i must pay them a call out fee of R 850,00 cash before they can start fixing the system .I want to call on all of us who was done in by these people to form a chat group with the intension to seek legal advise or even lodge a collective complaint. I feel strongly that we must stop them from continuing this exploitative behavior . and let them return our money