Turkcell Line Has No Reception Since Porting And Contract Cancellation Requested

I ported my mobile line to Turkcell about two months ago, and since then I have been constantly experiencing serious network problems. My line almost never has proper reception, and I cannot make clear calls anywhere. People often cannot hear my voice, my calls drop, and I cannot use the line properly in my daily life. Despite contacting Turkcell customer service about this issue, I have not received any satisfactory or solution-oriented response. The conversations were superficial, and my problem continues exactly the same. I feel that I am paying for a service I cannot use. Due to the ongoing network issues and the fact that I have been unable to use the line efficiently since day one, I request that my contract be cancelled without any penalty and that I be allowed to leave Turkcell without being charged any fees.