Worst experience ever

I got my phone last year December and immediately it had problems when I tried to report the phone problems they didn’t answer today when I report they are telling me that I have to take out money so they can fix the battery and bare in mind that it wasn’t my fault that they inserted a wrong battery in my phone they are ignoring me now and they don’t want to pay me back my money..DONT BUY FROM THEM RATHER BUY FROM THE ISTORE PRE-OWNED.. I get it used phones are not perfect but as a business acknowledgement your mistake and act accordingly don’t accept more money from the customer especially when they are not wrong