Mobikwik - Unnecessary charges levied by mobikwik

Hi
I am a regular user of pay later apps like simple , mobikwik , lazypay etc and have been doing all the payments ontime. However , my daughter was born on **th june and the events following the same, i missed the deadline of mobikwik repayment of ** july just by * day.
For the pending amount of **** they had levied a late fee charge of *** Inr. I called the customer care and requested fkr refund but they denied.
As per the policy of RBI, If a customer delays the payment by more that * days after due date then the banks and companies can levy penalties.
But mobikwik rejected all my plea and didnt waive the late payment charges.
After waiting for the resolution, i just paid the pending amount of **** which was my actual bill.
For the month of july, the billed amount was *** and they asked me to pay *** +*** ( late fees). I again paid the right amount but didnt pay the late payment charges. Now they are applying late payment charges on late payment charges.
As per the rbi guidelines banks need to wait for * days before applying late payment charges, i just missed that deadline by one day that too because of medical reason for which I have all the proofs but they simply do not accept at all.