My son is turning 10 next mth & I don't know what to do with his behavior?

A few mths ago I caught him stealing from me. I took away his privileges for about a week.A week ago I had a social worker at my house along with cops telling me I need to tell him it's not good to cry wolf. The cops acted as if I could control what comes out of his mouth.( My son told someone I was gonna strangle him because he called a little girl a *****) Then on top of everything else I caught him stealing from a department store. I was so upset cause I was gonna buy him the toy he stole but he showed it to me & when I was gonna pay the toy was gone. I noticed it in the back seat of the car & when I asked him about it he said I bought it. I looked in the receipts & it was not there I asked him again & he began crying. He said he really wanted the toy. I am low income & can not afford to buy him everything he wants. I am a single parent & have no one I can talk to about this. I don't know what to tell him in order to help him understand he's making all the wrong choices