Sonic Drive-In review: The car hop stealing

Yes it's Monday night June 27th I went up to the drive-in. I ordered two medium vanilla shakes one would know whipped cream. When the CarHop brought my order out she told me my balance was 907 I gave her $20 bill she proceeded to give me back a five and five ones with no change. I probably would have allowed her to keep the change had she offered it but instead she chose to steal it from me. This is not the first time I've had this problem at the Sonic it happens quite often and I'm really getting tired of it. I have worked at several different sonics in my past and we were always told that you offer every bit of the customers change back to them and that if they choose to give you a tip that was for your benefits and if they did not you were not supposed to ask for it or keep it because that is stealing.