All NBC channels freeze

For about a year, my NBC channels have not worked  they freeze and lock up non-stop, and all NBC channels are unwatchable. Why am I paying $450 a month if I cannot watch my local NBC station or any NBC channel for that matter? It was awful during the Olympics, the World Cup, football, baseball, and actually everything, when you accidentally turn on any NBC channel, you have to change it quickly or it locks up the box.