Turkcell Superonline Slow Internet Speeds and Unresolved Issues

I've been using Turkcell Superonline Fiber for about 10 months now. My package is supposed to provide 25 Mbps, but the actual internet speed I'm getting barely reaches 1.5-2 Mbps. While speed tests show no issues (as seen in the screenshot), the actual download speeds are terrible. Instead of 25 Mbps, I’m only getting 1.5-2 Mbps at most.

I contacted customer service, and they said that although my internet speed appears normal, there are issues with my signal causing frequent disconnections. They sent a technician who just pressed a button and left—no modem replacement, nothing. My issue remains unresolved, and I’m not even getting a quarter of the speed I should be receiving.

I'm tired of paying monthly bills to Turkcell for such poor service. Please resolve my issue immediately.