Bad Customer Service

In March 2022, I purchased an iPhone 13 Pro at Incredible Connection Clearwater branch. A month later, the phone's battery started to fail. I brought the device to the store, and the clerk advised me to use it and check to see if the issue persisted before scheduling it. I used the phone for 7 months, and it continued to have the same issue. When I went to the store, they scheduled the repairs; however, after two weeks, they informed me that the diagnosis test had been successful, so they sent the item back unrepaired. In December 2022, the battery capacity was 97%. Once more using the phone, the battery's capacity dropped from 97% to 91%, which is not typical. Additionally, the battery was now depleting more quickly than before, so I had to return the phone a second time. It was scheduled again, and I received the same response: "It has passed the test. However, if I want to replace the battery, I must pay for it out of pocket, which ridiculous is given the item is still covered by warranty." The tech consultant told me he addressed the issue with the regional manager, but a week has passed with no word. I called the store today to inquire about updates, but it appears that the Tech department staff is not doing their duty to help me. Instead of going back and forth, why can't they just solve the phone's issue or just give me a new, completely functional gadget as it is still covered by warranty?