Just chuck all of their mess onto their bed, and I mean everything, plates, washing, rubbish etc. Yes it requires a minute or 2 effort but not as much as putting everything away. Stop doing their washing if they don't want to put it in the wash basket or put it away. Don't buy snacks or goodies and do not give them money. Treat them like they treat you to show them it is unacceptable. Cancel their phone contracts, they don't deserve them and are.clearly too busy on their phones to respect you. The eldest are teaching the youngest to treat you like dirt, and if it's not stopped now you will end up with years of this as the youngest grow.