Loss of Bonus entitled after leaving the job.

Sir. i worked in a Swiss MNC for approx 4 years as Assistant Manager Business Development. Every year we were given 'X' target to achieve. in year 2014 my manager gave me and my team a target of 3 Cr , which was eventually met at the year end. when we were supposed to get the bonus we were told that actual target was 4 Cr and our Bonus was deducted since we could not meet given target of 4 Cr. Similarly in 2015 we were given target of 4 Cr by our Manager and at the year end we achieved the given target. in early 2016 i left the job and since i was entitled for the Bonus of Target achieved in 2015 i sent all the revenue achieved to my manager and other team mates. 3 months after i left i got my bonus 70% less than the actual bonus. When asked i was told that the revenue i shared was of other team members and i was a non performer. Since i left the job i had no option than to send email. I tried with Quality team, HR, Director but no one is giving response. I am ready to counter check all the details submitted by me before leaving the job. pls advice what i can do now? pls help.