Esty Oven Issues Persist, Requesting Replacement or Refund

I started using my Esty oven 9 months ago, and from the beginning, I had problems with uneven baking. The service came to check it but did nothing to resolve the issue. Later, the oven's interior light bulb burst, so I called for service again, and they replaced the bulb. Then, a more severe issue occurred—the oven shuts off completely during cooking, only to start working again after 30 minutes, disrupting the baking process.
I’ve called the service three times for this problem. They acknowledged a manufacturing defect and said they would take the oven to the service center but only replaced the fan instead. This issue has happened repeatedly, and each time, they replace a part. They even admitted the fan was inadequate. Despite the ongoing warranty, when I requested a replacement or refund, the service team responded aggressively, refusing further assistance and saying they would no longer come if I called.
I’m now formally requesting the replacement or refund of my oven. This situation is unacceptable for a product that is still under warranty.

