telephone modem resets

Why does cox cable claim there is an issue with equipment when the modem randomly resets itself. Mine resets itself regularly around the top of the hour at random times during the day. changed out modem. changed power source. had tech out and still have the same issue. Other voltage equipment using same sources do not have issues like this. Why is it cox does not admit to a deficiency in their equipment or the signal as the problem. They want to reset it after it has reset and is working again. Even when on chat where I will lose them if they do? Why do they lie to me and want more service calls when the problem is not in my house!