Turkcell Superbox 5G Speed Dropped After Modem Replacement

I am using the Turkcell Superbox 1 TB 5G package. After my modem was replaced last Friday, I started experiencing constant ping issues and significant drops in internet speed. I had never experienced this problem before, but my internet speed has now decreased dramatically, and the connection becomes unstable while gaming and performing online activities. As shown in the speed test result I attached, my download speed drops to as low as 4 Mbps.

I contacted Turkcell customer service about this issue and was told that I would be contacted, but no one has called me back and no technician has been sent. I have not received any clear explanation regarding the modem or my connection. Although the problem started immediately after the modem replacement, no one has taken effective action, and I continue to experience service problems.

I am paying approximately $31 per month for this service, and my contract is still active. Not being able to receive the expected performance from a service that I am still under contract for is causing me serious inconvenience. I urgently request that the speed and ping problems that started after the modem replacement be investigated, that my connection be restored to a stable performance consistent with my contracted package, and that an on-site technical inspection be conducted if necessary.

I request that Turkcell contact me through my registered phone number and resolve this issue as soon as possible. If the problem cannot be resolved, I request that my contract be canceled and that the inconvenience I have experienced be appropriately addressed.

Ü*** T***********
Contact No: 0 (545*********04