Harvey Norman laptop nightmare

I'm just looking for advice here if possible....

My little sister bought a laptop from Harvey Norman in September just gone. 1 month ago it stopped charging so said sister went in to see what the story was.

They sent away the charger to be fixed, WHY they did not just plug another one in to check it was the charger causing the problem I do not know. She let them do this, three weeks it took to get a "new" charger back....NOT WORKING.

She goes in today with it again, they advise they will send it away again , the laptop this time. Will take another 3 weeks. They refuse refund, and will not give her a temporary one either.

Now she is in her final year of college, she spent her whole grant on this bloody thing, and cannot study without it. ( I know I know a library would suffice), she claims she needs it to study point blank.

ANYWAY all of that is irrelevant really. I am just wondering If she has any rights here, being 6 weeks without a laptop she paid good money for that is through no fault of her own??

Or am I completely wrong ? Feel like going in there myself, I feel like they are fobbing her off because she's a young girl.

Thanks !!