Experience letter

Hello, Actually I left my previous organization in Jan this year and because of some personal family issue, I was unable to go to office as I was at my hometown. I had explained the whole thing to my Team leader that what was the issue which happened ( although it was very personal) however, prior to that they had already marked me as abscond. I requested them a lot about it as I never wanted to leave the organization and also no one from the management told me that they have done this. I got to know about this abscond thing 10 days after they already absconded me. Unfortunately, my situation during that time was so bad that I was even not able to access my phone. I requested them for the experience letter as I am looking forward to join a new company and they are asking me to pay my basic salary for getting the experience letter that is around 18K. Can you please suggest me that what will be the best way to atleast get any confirmation from their end that I worked with them? I have the offer letter and all the salary slips but I am just left with the experience/receiving letter. Kindly help me with this as I am in urgent need of a job.