Robery, unfair business practices and senseless point views Takelot

I ordered outside flood lights In a pack of 4. Takelot delivered three working lights and one defective one. I lodged a return request and they collected the light in question. To my surprise they say they can't replace the effective one because I didn't bring the whole pack of four. Now they say they can't replace the defective and they have declined my return and concluded the case.