I work in a newsroom. It is exactly like this. The TV producers don't pay attention to the web unless they have to tease it, they don't look to see if things exist, they don't even look at our front page half the time, and they don't proofread the things they put in that appear on the site. There's almost no accountability. And yet we're expected to kowtow to their every need, put up pages in literally three hours or less that are full of content, graphics, and features, and we just don't have the staff to do it.
The worst offender is the assistant news director, who never even logs into her Outlook e-mail account (the one the GENERAL MANAGER uses to send messages to people), never looks at our site (delegates other producers to do the job for her), never compares our site to other sites for ideas, and only really is polite to one member of the team who she used to work with, almost 10 years ago (the woman on our team has been with the station since the mid-90s, and was a TV producer herself before she moved to web). NOBODY in the newsroom likes her.
Unfortunately, in my business, you just have to suck up the work other people don't do, or else everyone gets in trouble equally.
The other example I have is our IT guy. He's competent, and really cool, but a MAJOR slacker and very difficult to find when you need him. If you can pin him down, he'll fix anything you need fixed, but pinning him down is like trying to catch a fly with chopsticks. The thing is, we don't want to get rid of him (no one in the web department does, anyway) because a new IT guy might come in and clamp down and put up blocks and take away all the open-source software that's not "necessary" for me to do my job -- like Pidgin -- or the other web browsers -- because all we really "need" is IE. That sort of thing.
I'm not saying my examples should guide your decisions, but before trying to get action taken against your slacker co-worker, weigh the positives and negatives of what a new co-worker at that position might bring -- and if it looks to make your job suck more, you might just want to stick with the slacker you have rather than the unknown quantity you might get.
Don't make stuff up, though. That's just bad business all around. I would say, if her position pays more than yours, try to supplant her instead.