6 month old Faulty Device that im not being covered under waranty.

I bought a Doogee S55 Lite on 7th May 2019 from cash crusaders and a couple of months later the battery started swelling badly to a point where it is putting pressure on the screen creating white spots and pushing the back cover outwards by quite a bit. i have contacted Geroge from Brakpan Cash Crusaders where he said that they do not warranty the battery, now i am unable to find a battery locally that renders a phone 6 months old useless. Not only am i unable to replace the battery, the phone is dangerous to use as lithium-ion batteries that are damaged (obviously mine are damaged) are a potential explosion and fire risk that can cause serious enjoy or even a fire in your home.