How to settle a civil case for credit card default after paying fine

I have some credit card defaults and I went to prosecution and cleared the bounced cheque with fine payment 2 years back. Now collections agency is mailing to HR, threatening via Whatsapp & phone calls.

The bounced cheque amount was 55K. Now the agency is asking nearly 300k. I understand the civil liability but what is the way out of this? Can they file a civil case and make a travel ban?