Bajaj Finserv — emi penalty charges

I nilam jadhav taken bajaj finserv flexi loan and my loan track record is good i pay regularly my emi amount but this month i fail to pay my emi of rs 8527 due to some reason but now bajaj finserv is charging a penalty of 3000 rs for emi of 8527 amt is it a legal way to charge this penalty amt what percentage they charging a penalty amt to me and what is the rbi guidelines for penalty charges amt and what is the percentage for financial comany permitted by rbi to charge penalty amount from customer