There are a large number of possible issues which could give you a right to challenge the termination of your employment in a situation like this.
Discrimination on the basis of age is covered under The Age Discrimination Act 2004 and The Equal Opportunity Act 2010.
If you were replaced by a younger, less experienced employee it may be that you have been discriminated against because of your age.
You should consider whether there were any statements made about your age in the period leading up to the termination of your employment. If for example, the company was engaged in a process of re-birthing itself with a young workforce you may be suspicious that you have been discriminated against because of your age.
Also, if you have a lot of accumulated sick leave it will be a windfall gain for the company to dismiss you because it will not need to pay out the sick leave at the time of your termination of employment. Older employees generally retain sick leave for when they need it, and regrettably find that a wrongful termination decision deprives them of that benefit.
Similarly, after seven years in employment, most employees accumulate ongoing long service leave. The company will save money from long service leave contributions if you are replaced with a younger newer employee. You will be disadvantaged because in a new job, if you can find one, you will need to work for seven years at least before you are entitled to any long service leave benefits. These are issues for you to consider and may make you sceptical about the genuineness of your redundancy.
It is unlawful to dismiss an employee from work due to a temporary absence or illness. Refer to the Fair Work Act 2009 (Cth) and Equal Opportunity Act 2010 (Vic) and the Age Discrimination Act 2004 (Cth).
The situation is worth examining if you have recently taken a few days sick leave or have been injured and have lost some time off work. Sometimes employers are quick to move against employees who have a lot of accumulated sick leave and because they are fearful that the injury or the illness may result in substantial payments to the employee and the loss of the services of that employee over a lengthy period. By making that employee redundant in what is commonly known as a no fault termination of employment, with a minimum redundancy payment the employer can save itself the need to pay out the sick pay.
Another issue is whether or not you are entitled to enforce the higher payment promised to you, rather than the lower payment made to you.
You should be aware that often large corporations have policies describing the entitlements of employees to redundancy which are greater than the minimum under the Fair Work Act 2009 (Cth). You should check out the company’s policies to see whether or not you are entitled to the higher payment.
If the company will not provide you with a copy of its policies, you may be able to commence legal proceedings to obtain those policies, without necessarily committing yourself to sue for the higher amount.
Alternatively, if you have not signed a deed of release, you might still demand payment of the higher amount on the basis that the lower amount is the minimum amount but the law requires the higher amount to be paid pursuant to obligations of the employer to provide not only a redundancy but also reasonable notice of termination of employment.