Goldair 3 panel gas heaters multiple product defects

I recently purchased 2 Goldair 3 panel gas heaters. To date i have had to go back to Builders Warehouse not only to swop out the 2 that i purchased, but to swop out each of the 3 "new" ones that i was given as a replacement. I am unsure how these units pass a safety or a quality check due to the issues i have experienced with them. Each time I land up having to go back to Builders to swop them out.