Maybe it's because of your reaction that your kids not listening
Maybe it's because of, "why are you always nagging!?" That they can't stop nagging
Maybe it's because of, "are you deaf?!" That they keep not listening to you
Maybe it's because of, "stop acting like a brat!!" That he won't stop crying for that toy in Walmart
Maybe it's because of, "I've gave up on you, you'll never be a good girl like your sister." That won't make her start acting in a respectful manner
Try changing your word, your reaction, your mindset, maybe that's the main problem