Battery problems

I would like to complaint about istore online pre owned, i bought a phone last month and the batter is damaged I sent them communication they requested my order number that was two weeks ago to date they haven't said anything

I'm really disappointed with their service

I thought all the pre owned phone went through checks how can they sell me a phone with damaged battery? When I go to setting the error message said the batter needs to be replaced? Who should replace it me? After buying a phone only last month they should have mentioned it has a battery problem was not going to buy it call me on *** email *** Order #PLG59907