Premiums increased by 63%

Discovery just increased my premiums by 63% in a single year. Is this legal? I don't know. This is ridiculous. I called the call center. I sat on the phone for an hour, and still didn't get through, so I got onto their chat support line. I waited an hour and got booted. I waited another hour and was told they moved me to the highest income bracket, so if I don't fall within that bracket, I have to submit some kind of form. I don't see that this could be legal. 64%? Really?