Does a car need to be registered to show ownership?

My car was towed and I have the signed title but I never registered it because I could never get it smogged. I didn't want to waste the money cause I thought the state could make me junk it if it couldn't p the smog test. now the towing company won't let me get into the car until I register it. They say it still belongs to the woman who sold it to me and the title isn't enough. I know they are wrong but what can I do?