Here's an equivalent between parent and daughter:
"She will deliberately do things she knows she's not allowed to do"
She thinks you are wrong about not letting her do those things. Either a) you haven't explained or shown why sufficiently well or b) you might be wrong. [and remember that a gesture may communicate more than a word and a sentence may communicate more than a paragraph - if you can't explain and persuade in less than 15 seconds, you maybe don't actually have a very clear and rational reason for forbidding the thing...]
"I have started sending her to her room telling her she can come out when she's
(This is a parent who complained that her child doesn't listen) From her point of view, that's got to look as if YOU don't listen!!!
"Something as trivial as her asking for a drink and being told "in a second
babe" can be enough to set her into a full blown rage and I can't handle it any
Don't worry - this one is easy. You say "yes of course you can have a drink. Do you want to get it yourself right now, or do you mind if I quickly finish up what I'm doing and then get it for you?" If she wants you to get it immediately? I'd be inclined to get the drink straight away (that's got to be better than rage), and then in future make sure there are drinks available near her so you don't have to fetch all the time. I know a man who used to keep a stack of bottled water by the side of the couch so that whenever his wife said "can I have a drink please?" he could say "yes of course darling" and hand one over without missing a moment of the footie...