The following legislative provision sets out the requirements for an IFA:
and the following guide explains how IFA's explains further in lay terms:
Notably they should not undermine minimum workplace rights and overall any arrangement should not leave workers worse off than if they were simply governed by ordinary employment rights. It is therefore utterly implausible that your IFA would entitle your employer to demand that you work 80 hours a week without being compensated for the work you are performing.
You should ask for a copy of your IFA and see what it says about your pay and hours of work. If it doesn't say anything you need to look at your award for the base conditions relating to hours and pay. Whilst some occasional excess hours unpaid may be acceptable within reason, the general position under the Fair Work Act is that employees cannot be asked to work more than 38 hours, and whilst an IFA may vary this, it would have to be accompanied by compensation to ensure the IFA meets the requirement that a worker won't be worse off overall.
If after reviewing your IFA it appears your employer is not entitled to force you to work the extended hours they are demanding. You should therefore discuss with your employers whether they intend to pay you for excess hours and if not, refuse to do more than appears reasonable. If they take action against you for refusing then you likely have grounds for a general protection claim or an unfair dismissal (if they sack you). Strict time limits apply, particularly if you are sacked (you have only 21 days from the date of dismissal), so you need to act quickly.
You can find out more about general protection claims and unfair dismissal claims here:
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