How to handle a 11 year old boy disobeying rules?

my son who's father has not been in the picture has an attitude and a issue with following my rules. he constantly is getting in trouble at home and at school, i have tried grounding him he has had detention at school, i have taken about sports, going places with his friends, ps3 games everything, but he just won't learn or listen. I have even stopped him from going to his grandparents because he does whatever he wants and they don't follow my rules. His step dad is trying to inforce my rules and support me as the mom. no matter what we do even threaten him it doesn't matter. i have taken him to cavs game, hockey, kalahari dave n buster's bought him things and no matter what rewards eventually he ends up breaking rules. one rule is i have to repeat my self and he talks back. the other rule is that he needs to check in if he goes to a friends house and ask permission to go anywhere. he has a curfew of 9pm. he has chores to do for allowance but if he breaks a rule he still has to do the chore just wont get the allowance. trying to find a happy median. any suggestions?