Bully on the School Bus

My little boy home home from school the other day and was very sad getting off the bus. He said his friend D pinched him on the face. He had marks all over his face and they are still there. Yesterday he got off the bus and was sitting in the front seat. When he got off his little face was so sad. I asked him how his day was and he said i was on green today mommy. I asked him why he looked so sad he said D bit him in the tummy. He lifted up his shirt and there in the middle was his skin raised and blood coming from it. I was mad and came home cleaned it off put a band aid on it and called the bus director. He said that if the bus driver moved him to the front than that should take care of it and that it was a permanent thing. I talked to a few mothers yesterday who said I should have taken Deano over to the little boys house and show his mother what he had done. I was not sure if that was what i was suppose to do . I dont want to be a complaining mother but they just cant do that to my baby. When i took Deano to the bus stop today i asked the bus driver if he knows that dean is getting hurt by the other boy and he said well no. Deano doesn't tell me. HE said that He gets on to dean for doing something but had no idea that someone was actually hurting dean. WELL NO CRAP MR BUS DRIVER.
I am so sick of these Adults that have our children in their care. they are quick to judge and punish but do not try to figure out what started the situation in the first place. Dean has been getting into trouble for defending himself and nothing is being done to the ones who are hurting them. I think this was my last straw from now on. If someone else lays a hand on him and its not taken care of they will get a long loud earful from me. What the Heck is wrong with these people. And some kids dont stick up for themselves . Just like dean yesterday. Someone bites him draws blood dean did something back i assume from what the driver tells me but then dean is the one punished with out question and then put in the front by himself. So now hes sitting there hurting physically, and now emotionally hurting because he did nothing wrong( in his eyes but protect himself and hes being punished) No one on his side to help him. ITs like he was left all alone . I am having a fit and it kills me that he has to go though this.