releving letter from the employer

First, mobilize through some sources to repay the existing loan with the past employer (personal loan from NBFC) and then demand for such experience certificate from the employer.  An employee of a financial company not capable of raising a loan for repayment is a surprise.  If your employer is willing he may treat your loan as finance to public from date of your resignation.  What about adjustments towards terminal benefits such as PF, Gratuity etc.,  What are the exact reasons for your termination of the job ?  What was the purpose of the loan ?

You have not posted the material facts.