No paid leaves during probation is being twisted out of proportion

I'm a fashion designer currently 1 month into probation. Just received my salary and it was almost 7k less than the total, mind you I had taken only 2 personal days. Upon asking I found out my money is being deducted for Sundays aka 4 paid leaves and was also informed that money would also be deducted on days when the office will be closed for public holidays. Yes they did mention that I wouldn't be given any paid leaves but never would've thought it would be for Sundays. When confronted, the excuse "company policy" was given even though I've never seen any document or rule book of the company since the day I've joined. How is this fair or legal? Please help