Change of resignation period

So a question for my dh. He has resigned at his current position due to receiving a new job offer. He wanted to do the right thing so gave 5 weeks notice to help the transition period so he could hand over to his replacement. He works in a senior financial role and due to the time of the year thought it would be necessary. His current employers however are being absolute nightmares and making his life a daily struggle. His notice period as required by his contract is 2 weeks. He has already served 3 weeks of the 5 he gave as notice. He is wondering if there would be repercussions to his payout and monies owed to him if he changed his notice period to ending ASAP as he has served out contractual notifications or if he is bound by the written notification of resignation he gave.

I have been searching online but am struggling to find the right info. I know if the resignation is withdrawn it needs to be agreed on by both parties but cannot find anything pertaining to this issue. Any help would be much appreciated.

I'd probably give fair work Australia a call, then they can give you the exact and correct info

I did give them a buzz but they were unable to give me any specifics..... Apparently it's a bit of a grey area that could require independent legal advice as it's outside their jurisdiction and the law doesn't mention anything around this type of circumstances.

Oh, well that wasn't such a great suggestion on my part. Sorry!
Hope someone else can help you out :)

No not at all, thanks so much for the suggestion!

He will probably need to take it as annual leave. But I would probably talk to the boss and say "I can either take it as annual leave or terminate now". I don't think he can change the notice period the way you talk about though - if that makes sense?