I Face Ongoing Reeder S19 Max Performance Issues and Unfair Paid Upgrade Offer

I have been using a Reeder S19 Max 128 GB 4 GB RAM phone for about 3 years, and I have been experiencing serious problems with the device for a while. There are constant issues with the sound, the network connection is unstable and problematic, and the camera performance has deteriorated noticeably. These problems make it very difficult to use the phone in daily life. Because of these issues, I contacted Reeder's customer service and explained the situation. Instead of offering a solution for my current device, they suggested that I pay 5,400 TL to switch to a higher-end model. I find this offer unfair and unacceptable because the problems I am experiencing are caused by the device, and I expect the brand to stand behind its product. My clear expectation is that my phone will be replaced with a new, problem-free device free of charge or that I will be refunded. I request that my grievance be resolved as soon as possible and that a fair solution be offered without demanding any extra payment from me.