Section 13 of the Employment Act is quite clear about this but unfortunately you are not covered by it. Unless they have very valid reasons, I don't think they can do much if you choose to pay indemnity in lieu. Do consult the Industrial Relations Department for another opinion.
13. Termination of contract without notice.
(1) Either party to a contract of service may terminate such contract of service without notice or, if notice has already been given in accordance with section 12, without waiting for the expiry of that notice, by paying to the other party an indemnity of a sum equal to the amount of wages which would have accrued to the employee during the term of such notice or during the unexpired term of such notice,