RTO India — Extra cash collected

My vehicle no is KA51AD4919
I have paid 3500 for permit in hosur rto office because they told me that to pay 3500 but in slip added me that CF case without any reason actually the permit cash only 3000 but for extra payment 500 they collected I ask why reasoning collecting extra payment suddenly they put a case for those extra money please check with rto divisional office to make sure to resolve and take an immediate action on it

Thanks and regards
Sathish kumar K