Suit filed,wilful defaulter written of settled in experian

I use PAYTM POSTPAID,which provides loan facility through their nbfc partner ADITYA BIRLA.Upto the month of JULY,I had paid all the dues on time which is 7th of every month.For the month of AUGUST,I had paid my dues amount on 7th August which was not getting reflected,so I had asked them for the status which they said it has been received and is updated.The very next day I got call from customer care to pay the dues amount,where I mentioned the order I'd of the payment with the chat I'd for the same,after which they said it has been updated in their system.As I stopped getting calls from them and was already verified by the customer care service that my amount had been paid,I got relieved for clearing my dues amount.This month on 27th of September I got call to clear my dues amount for the previous month,which for me was already paid.Hearing this I immediately contacted customer care service for the same where an auto generated message was displayed.The same day I checked my cibil and got to know the amount was still due.So the next day I asked about the amount remaining and requested waiver for the same.So on 29th of SEPTEMBER I paid the amount which was discussed previously and they immediately contacted to verify the same and told me it will be updated in a week.Hearing the previous issue they advised me to mail all the same both to PAYTM POSTPAID and ADITYA BIRLA about the issue dealt with customer care service. Upon rechecking my credit score,though CIBIL showed no changes, EXPERIAN showed it as suit filed,wilful defaulter, written off settled and the account marked as settled.After Googling these terms I came to know it's a black indicator for credit and worst suit filed and wilful defaulter is a more serious issue.So I had mailed them i.e grievance@paytm and ADITYA BIRLA for marking me as WILFUL DEFAULTER,SUIT FILED and to remove the same as I had paid the amount. I need assistance as to what should I do further to remove this as it's a serious black mark in credit report