Sennheiser Cx True Wireless Sound Problem!

As a recent purchaser of the Sennheiser CX True Wireless headphones, I am very disappointed with the sound quality. Despite spending a considerable amount of money on these headphones, I have found the sound level to be insufficient, particularly when it comes to phone calls. It's worth mentioning that my previous Sennheiser CX275s, which I bought three years ago for only 150 TL, provided a better sound experience. I am really unhappy with the performance of this headset and would like to request either a replacement or a refund from the company. For a premium product like this, I expected much better quality and functionality. I want Sennheiser to take this issue seriously and offer me a satisfactory solution as soon as possible.