Turkcell Superbox Low Speed

I have been using Turkcell Superbox with a 500 GB package and a ZTE brand modem since the beginning of my subscription, but I have never been able to get proper internet speed. From day one, the speed has been around 1–5 Mbps, which makes it very difficult to use the internet for even basic needs. I contacted Turkcell customer service about this ongoing low-speed problem, but they did not provide any effective support. They said they would call me back, but no one called, and the issue remains unresolved. I request that my Superbox connection be checked in detail and that the speed problem, which has been present since the start of the service, be permanently fixed as soon as possible.