How Should I Handle a Bonus Clause Change Without My Consent After Joining?

I received an offer letter from a company stating that the joining CTC would be 4.50 L per annum, including a development bonus of 90,000 payable upon successful completion of one year. Upon joining the company, they provided me with an appointment letter. However, after completing my first year, everyone received their bonus except me. The reason for this is that the appointment letter given to me stated that the development bonus of 90,000 would be payable upon successful completion of 2.5 years.

I questioned why they altered my documents without my consent, and even the CEO was unable to provide an explanation for this. What should I do now?

"The reason is that the appointment letter they gave me stated a development bonus of 90,000 would be payable upon the successful completion of 2.5 years.

Didn't you check your appointment order when you received it, signed it, and returned it to the company? Go and speak to the company, show them the offer letter, and ask why there is a change. However, there is also a failure on your part for not noticing the different time frames in the appointment letter and offer letter. If they don't agree, the only alternative is to quit or accept the fait accompli."