I have a 14 year old boy who has the same attitude. While I do believe that teens are going through a lot - hormones, high school, unrealistic views generated from popular TV shows - I do not tolerate disrespect from my son.
So, if he is horrid there are consequences. He has a cell phone - he is to answer it if I call. If he does not, I take the phone away. AND, I answer it when his friends call and text back to them telling them I took the phone. Guess what, I only had to do this once. He also knows that it only takes me one phone call to disconnect his phone service and he knows that I will do it if crosses the line. Cellular phones are privileges, not a right.
If he is disrespectful I don't argue, cajole, or try to talk him out of it anymore. I very pleasantly remove privileges. TV, Computer, PS3 until he apologizes and behaves respectfully. I have literally pulled the power plug on his PS3 while he is playing on it.
I do control what he watches on TV and what websites he can visit. I use parental blocks and most TV watching is done in the family room. In fact, all major electronics are in the family room. When he is in huge trouble I disconnect the TV in his room.
I have been known to take doorknobs off bedroom doors when they are locked against me and once threatened to remove the door completely after he slammed it in anger. He no longer locks nor slams his bedroom door.
Does you daughter have defined chores? My son does. As I tell him he is a contributing member of this household, and while homework comes first, once that is completed he does dishes, his own laundry, etc.
You must have rules, and one should be to always speak in respectful tones to the other members of the household. The other should be that whatever you (and your Fiancee) say is the rule. You must have consequences and you must be consistent with them. The same consequence every time for the same violation.
Sit down and calmly outline the rules and consequences to your daughter. Put it in writing and post it on the fridge. Live by it.
Do I like coming down hard on my son sometimes? No, it hurts me to punish him. BUT, it is my responsibility to raise a respectful, contributing member of society; to teach him that he is not entitled to anything just because he exits, and to teach him how to be a member of a family.
And you know what - he is a nice, helpful boy. Well, about 90% of the time. LOL
Good Luck and stay strong.