JBL Reflect Fit defective units shipped but not yet replaced under warranty

I purchased a JBL Reflect Fit online and received it last month. Upon receiving the product, I discovered that there was no sound coming from the right earphone. I immediately contacted customer support to request an exchange, but was informed that they do not accept returns because the box had been opened. I then sent the product back for service, but this process took 10 days and the issue was not resolved. After this, I was informed that a new product had been sent to me, but again there was no sound coming from the right earphone. I contacted customer service again and was instructed to send the product to the Aztek company's service center in Istanbul. I did so, but at my own expense as they refused to cover the cost of shipping. Even though I was willing to pay for the shipping, they sent it back to me without any prior communication. This resulted in me having to resend the product at double the cost and further delay of 10 days. I have now been waiting for a resolution for over two months and have not received any satisfactory response from the Aztek company. Furthermore, I have researched and found that there are multiple complaints about the same issue with the right earphone, indicating that there may be a compatibility problem between the inner parts of the product and its outer plastic cover. The product is 50% more expensive than similar products on the market, yet the service I have received is unacceptable. I hope that the company takes immediate action to address this issue and provide a satisfactory resolution.