Cellphone Purchase/Refund

I bought a new phone from Edgars Mall of Africa,after testing the phone and found that that it is not compatible with our corporate security apps,failed to join the device into our domain and the IT dept deem it unfit for corporate use,I tried to return the phone as I still have all the accessories intact including proof of purchase,Edgars is refusing to refund me or credit me for another compatible phone,I spent to much money in this shop for them to give me such bad service,they dont even wanna hear my story,they refered me to a lady called Germina which never bothered to assist me,Im a very UNHAPPY client .