Dismissal help

[bob^]

Gday, today my gf got the sack from a store she has been working at. She has been there approx 3 months (6 month probation), and came back from a 2 week holiday today to get the news from the area manager.
The reason the area manager gave was that her skills aren't up to the standard they should be, but 3 weeks ago when the same area manager gave her a review, she said she was progressing extremely well and is doing a good job. The two stories contradict.
When she went for the job, she informed them that she had been planning a holiday, and just needed to book, but if it was a problem then she wouldn't go. They told her it was fine, and the area manager at the time took it all through the right channels to get approved.
It seems as though the new area manager didn't like the fact she took the two weeks off, even though the previous manager said it was fine.
Does anyone think she has some kind of leg to stand on? Or is it best to just walk away?
Neither of us know who we can talk to about advice, as we have never had to deal with something like this.

Thanks