Help

im struggeling to get respects from my 7 and 4 year old! They gang up on me and thinks everything is a joke. ive had the flu all wkend and woke up monday morning feeling really rough. I went in to speak to my older daughter to ask her nicely if she would be helpful this morning and get ready for school and help out as im poorly! She didnt listen to me at all. She took her time getting dressed and started winding up her little brother by hidding his toys. She would get into a really silly mood with him and they would be really silly to wind me up on purpose. I just get upset she can be so selfish. I have tried to ignore the behavior but nothing seems to work.