My Philips Vacuum Came Defective - Trendyol Refuses to Refund Me

We purchased a Philips vacuum cleaner, and it arrived defective. We returned the product, but they sent it back claiming we had used it. We explained that it was impossible to know it was defective without trying it, and it had only been used once for testing. We requested a refund, but they said we needed an official report from the authorized service center. We obtained a wet-signed report from the authorized service, which also provided a brand-new boxed unit and confirmed that we could return it with this report. We returned the product again, but instead of refunding our money, they sent the product back once more. Trendyol is also not helping with this issue. We purchased it thinking Trendyol was a reliable site, but their actions have been far from reassuring. I am requesting a refund.