Diwali Bonus Unpaid

I work at a reputed(ish) finance company which I joined as an intern in July and as a permanent employee in the middle of October. My signing of documents was done within that and I was already working during Diwali but I was not paid a Diwali bonus.

At first, I understood naturally that I just joined so expecting a Diwali bonus would be stupid. But then I just got my first salary payslip which paid me for 46 days, 16 days of October and 30 of November. Moreover, my CTC details clearly state that my Diwali bonus is reduced from the total amount offered to me when I join, which in turn reduces the amount I receive per month when I'm paid my salary.

I mailed them about this and they responded saying "since your new joined data is received in the month of Nov24 hence Diwali Bonus will be paid in next Diwali" so I asked them to remove it from my CTC because if they can't pay it to me then they shouldn't be allowed to reduce it from my yearly salary.

But this is my first job ever and I would love some advice on this. What do I do if they still rebuff my request? Am I being petulant or something? Thanks in advance