Refund

I bought an IPhone 7 Plus two months ago. It had problems with the phone disconnecting or the person on the other end couldn’t hear me . I took the phone to the Apple store. The technician reinstalled the software ware. I brought the phone home but the problem existed. I took the phone back to the store and this time they took my phone and the technician brought another phone in a white thin box, took the SIM card out of my phone and inserted to the so called new phone. Right there I asked if that phone was refurbished and he denied that. I didn’t believe that and asked the store manger if they were giving me a refurbished phone. He also ademently denied that. I had no choice but to take a new phone and come home. I am very upset because the staff lied to me as I did get a refurbished one. Also I don’t like to have a second hand phone when I just spend around $700 for a phone less than two months ago and I didn’t do anything to cause a damage to the phone. I really want a refund so I can buy a phone from another company. What do you advise?

Thanks