How do I get DD to apologise???

[Olive]

She is driving me crazy! DD3 is difficult at the best of times, we're having major issues atm and one issue that turns into a huge and very long tantrum/screaming is getting her to apologies, she cries, screamed, calls mummy over and over and over again, I don't understand why she can't/won't do it,
I've just asked her to say pardon after farting and the same thing is happening.
I need help desperately as this will go on all day.