I think you did the right thing and Sandy needs to take responsibility for her daughter. If Debbie is an out of control rude little brat this is Sandy’s fault for being a lousy Mum and not teaching her to have manners and respect for other people. You have done nothing wrong here and I personally think you should go over Sandy’s house one day and have a nice chat with her about her daughter’s behaviour and tell her it is unacceptable and you have had enough of it.