Oppo Reno 14 Pro Keeps Missing Incoming Calls

I purchased an Oppo Reno 14 Pro from the Vatan Bilgisayar online store. Since the day I received it, the phone has had an ongoing network reception issue. Even though the device is powered on and shows a cellular signal, people trying to call me are frequently unable to reach me. They tell me my phone appears to be turned off or unreachable. This has not happened just once—it has occurred repeatedly at different times and has been reported by multiple callers.

At first, I thought the issue might be related to my mobile carrier, so I contacted my service provider. After checking my line, they confirmed there were no problems with my service. I then contacted Oppo's authorized service center several times and eventually sent the phone in for repair. The device was returned to me, but the issue was not resolved in any way. I continue to experience the exact same problem.

A phone that I rely on every day should not randomly become unreachable. Missing important calls creates serious problems for my personal life, work, and even my safety. I request that Oppo permanently resolve the defect with my device. If the issue cannot be fixed, I request a replacement phone. If a replacement is not possible, I ask for a full refund. I would appreciate a prompt resolution to this ongoing problem.