I’ve had enough!!!

I really am at the end of my  I seem to have a teenager in the house and she’s only 9 well 10 in 2 weeks but ohh my the attitude and the strops are really starting to grind me down.

It happens a over the most random things be it me asking her to help around the house her reply is “Why is it always me, you never ask Imogen to help” “no, not doing it” “Why should I?” “I always do it” she will even slam doors, speaks back to you with south attitude I want to scream at her, stamps her feet walking and her fab thing is stamping up the stairs.
So when I explain why I’m asking her to help
1. She’s old enough to help around the house.
2. If she wants money on her phone then she has to earn it or if she wants nice things she has to earn it.
3. She should be cleaning up her own mess.
4. She should do as she’s told I am the parent.

I still get the same attitude or she will then just not talk and even take me on she will just sit there staring  at nothing and completely ignore anything I say to her.

She will also take it out on her sister being mean and talking to her with an attitude which then they start arguing/fighting.

There are times when she’s an angel and does everything I ask but the grumpiness and attitude are by far out weighing those.
I really am at breaking point in a previous post I said I was going to enjoy every day of the summer holidays well I can tell you I have failed at that…. I’m tired of it all… I feel like I’m running out of ways to deal with her.
HELP! If you have any ideas which may help this god awful transition time it would be great 

Thanks for reading my ranty post.