getting my kids to listen HAHAHAHA!!!

So I have a serious problem with my almost 3 yr old (this sat is her 3rd bday) and my 1 year old and listening. They say the terrible twos are the worst but when does that end? Really she is almost three and she refuses to listen to anything I say!! I have threatened to cancel her birthday party and to tell Santa how bad she is being so she will not get any presents but still it does not work. She decides to pick on her sister at the worst times like while I am trying to get school work done or take a test or RELAX!! LOL. I love them dearly but CALGON take me away!! She does the most awful things to her baby sister like shove her down on the floor sit on her throw toys at her then my one year old retaliates by biting, pulling hair, hitting with toys and so on all while their dad is trying to sleep because he works the night shift. Sometimes I think I am going crazy!! What is a mom to do to get them to get a long a little better they are so young and close in age I think they are just going to fight like that. Who knows? Oh and going to the store that is like pulling teeth to have a nice trip to just get groceries. I dread having to get groceries any more it is awful one is pulling everything into the cart and the other one is screaming and I hate that I dont want to be the mom that everyone stares at to shut there kids up!!! HELP!!! LOL!