Do complain to the bus company, but remember, failing to give you three feet is a small offense compared with actually hitting you. The argument that he could have hit you is a much weaker argument than actual hitting would be.

Don't expect to change anyone's behavior. Now you know bus drivers will do this. Expect them to do it again with complete impunity. Learn to expect it and defend yourself against it in various reasonable ways. As FBinNY says, take the lane when you must. Then quickly let others pass as soon as you can. One technique I have developed is turning my head back frequently. I do it not so that I can see but more to signal to others that I know they are there and I know where I am in relation to them. They treat me well as a result. Try it. Practice on an empty road: ride in a straight line while turning your head back frequently.