Good day, 

Based on the information provided, a company that falls under a bargaining council or specified  industry must follow the collective agreements entered into by the bargaining council. When trade unions strike they enter into collective agreements and once singed they are in force and effect. 

I would advise you to call your industries bargaining council to find out if there is a collective agreement in place that regulates the amount of leave days entitled to workers in that industry. 

If this is not the case then lodge a internal grievance with your company and challenge the company policy.  

Kind regards 

LP