Nissan Qashqai Fan Noise Issue Was Never Properly Fixed

I have a 2019 Nissan Qashqai 1.5 automatic, which I purchased brand new (0 km) from Baykoç in Türkiye. All maintenance has been carried out there, and the vehicle has never been taken to an independent workshop. For about a year now, whenever I turn off the engine—or sometimes even when I turn on the air conditioning—the fan runs extremely loudly. I first mentioned this issue during a service appointment at Baykoç a year ago, and they told me it was completely normal, but I wasn’t convinced. Later, I brought it to Baykoç and they also dismissed the issue or said they couldn’t identify the cause. Eventually, I heard from another source that Baykoç's Nissan contract was about to expire, which explains their lack of interest. I then contacted Efe Nissan—they promised to call me back but never did. After emailing Nissan Türkiye, I was directed to the Otomol service center. To their credit, they at least acknowledged that there was an issue and suggested it might be the thermostat (though they said this with only 50% certainty and didn’t explain how they came to that number). They didn’t have the part in stock and had to order it, so I went ahead and paid around ₺7,000 (approx. $180) to replace it—only for the problem to persist. Now they suspect it may be related to the fuse/relay box (IBM), but again, it's based on guesswork. That part costs around ₺17,000, and thankfully they advised not to order it yet. They told me they would compare it with a similar vehicle if one came in. It's been three weeks, and I’m still waiting. Here’s the real concern: Nissan is a global brand—surely this problem has occurred and been resolved elsewhere. Is there truly no communication or shared knowledge between your service centers? Why does each center rely solely on its own limited experience? If this is a known issue, it should be fixed immediately. Also, why do none of your service centers seem to have basic spare parts in stock? I’ve waited weeks just to receive updates. At this point, please just recommend a trustworthy independent mechanic so I can finally fix this issue and sell the car—I’ve had enough and will never consider the Nissan brand again.