Warranty

I have purchased iPhone 8 on December2018 and got one warranty at the time of November 2019 there is an issue of software then iPhone store has replace the phone and give me new iPhone and they also said that your warranty will also increase to one year upto December 2021 . But the new phone which is given my store in that there is also issue of speaker and when I have checked this one to repair store iPhone then they said there is no warranty of phone. So can please suggest now what should I do ??