OPPO A16 CPH2269 Has Severe Lag and Overheating Problems

I purchased an OPPO A16 CPH2269 through Trendyol. Since the day I first purchased the device, I have continuously experienced problems such as severe lag, excessive overheating, apps installing on their own, applications crashing, and the phone occasionally being unable to find a mobile network.

Because of these issues, I am unable to use the phone properly in my daily life. I contacted an authorized OPPO service center and handed over the device for inspection. However, they returned the phone to me without providing a permanent solution, and all of the same problems are still occurring.

I believe the device is defective. I request that my phone be permanently repaired, replaced if possible, or, if deemed appropriate, that I be offered a clear solution such as a full refund to resolve the inconvenience and loss I have experienced.