a difficult teenager

I am humbly asking for advice.  We have four children.  18, 16,13, and 8. A boy and then 3 girls.  We have wonderful relationships with all but the 16 yr old girl.

She was the easiest baby and toddler and a wonderful child to be around until she turned about 8.  I have no idea of anything in particular about that time period,but from then on she morphed into a different person.  She is never really satisfied or thankful.  She is easily angered by any or all of us.

She is not a warm fuzzy person.  She is easily offended and walks around with a chip on her shoulder all of the time as if she is just looking for ways to be offended or reasons to be mad. She tries to be surface respectful at least, but she is slipping more and morein that area lately.  She blames me for everything in her life that isn’t perfect.  She offers little help, only doing what is good for her.  The others are so much more helpful. She is hot or cold with her siblings and often talks to them so disrespectfully.  They are not that way with her.  She is bossy and judgmental towards them.

We have given her every opportunity in her passion for ballet that we can afford.  We have spent far more on her than on any of the others.  She never seems to be thankful for it or even really acknowledge it.  She does have a part time job.  She only does the bare minimum of schooling and complains often that she doesn’t like school and wants to be done.

We sent her many states away this summer when she was accepted into ABT’s summer ballet program.  It was a financial mountain for us but we figured it out.  Now she is so angry with us and telling us that we don’t care about her feelings because we didnt get her a car like we did her brother – who by the way got a $500 truck that didn’t run and we worked just enough on it to get it safe enough for him to drive.  We just gave him $1000 toward another used car.  He paid all of the rest from money he saved by working for a year and a half.  We said she can have his truck.  That is not good enough for her.  But it was great for him.

We told her all along that all that we were spending on ballet was why we couldn’t do anything else for her. We sold our home this year and were able to get into a wonderful new home. She actually has insinuated that we should be able to afford more for her if we could do that.  I am thinking how dare she insinuate such things regarding our choices.

I am shocked at her attitude regarding this.  I think her heart is far harder towards us than we originally thought.  Have any of you any advice on how to deal with this type of hard hearted unthankfulness with a teenager.? We feel we’ve done well with our children otherwise, but she is really difficult.