Experience letter and background verification

Hi All,

I worked for a small organization for 2 years and left that organization with one month of the Notice period, As per company norms notice period was for 2 months. 

If anyone serving one month notice then, he/she need to pay a two-month full salary including PF amount. 

As I served one month notice period, So they charged two-month salary.

I had paid one month salary. So, they gave me resign acceptance letter and told me that once you paid the remaining amount then we will release experience letter.

Now, I'm facing an issue with my background verification, which is done by my current company. BGV team told me that your previous company not doing background verification. 

So I connect with my previous company HR and she told me that you will pay the remaining amount with late fine, then only we will verify. (there was no clause for late fine)

In this case what action I can take or what are the best ways to short out the BGV issue.

Thanks,