Hisense policy

I have my hisense phone for 7 months. It is a contract from Mtn. I took the phone in the battery was only charging till 75 %. My phone is at mtn already for more than a month. They let me know today it's the battery It will cost me 299 for replacing the battery. So I told them to leave it I will get my own battery. They rep**** but it's the original battery. Is that not what was supposed to be in my phone. Maybe it was not. First time in my life that I have a brand new phone and 6 months later is default. Also they told me the battery is only covered for 6 months. Mine was just over 6 months. Thanks Hisense. I bought my first phone from you and loved it ...so upgraded to a newer phone. Never again will I do that again. I will also not recommend hisense to anyone . Thanks for being without my phone for nearly 6 weeks. I still don't have my phone.Borrowed a phone.