S84 Premio

S84 Premio cellphone. I bought a Premio S84 in April this year and today marks almost 7 months and the battery is swollen and it switches off at 80%. Mind you I am only using this phone for calls only since I have another phone I'm using for social networks. It shouldnt be like this. I only charge the phone once or twice a week .I have a reason to believe that Ackermans is selling us defective phones which is really absurd. I tried taking it back to the store I bought it from since I still have the box and the reciepts, they said they cant help me . What kind of customer service is that? I wont recommend to anyone to purchase these devices, I feel like I was ****med!!!