Facing a 40k Deduction: Do I Really Owe My Former Employer for Mistaken Salary and Leave?

Hi Seniors, I was on medical leave (UNPAID) from April to June. During the month of April, I was paid the salary—I accepted it as I thought it was my VPI amount. In the month of July, I worked for 9 days and then left as it was taking a toll on my health, and again, I was feeling sick. During my full and final settlement, my HR deducted the April month's salary, stating that it was mistakenly paid, and also deducted 10 days of leave, stating that I have 11 days prorated basis leaves, and I consumed 21 days leave, so they are charging me for 10 days.

Now I have to pay 40k to my last company. Please help me in understanding:

1. Do I need to pay for the mistakenly credited amount to my account (April month's salary) that wasn't indicated to me during my tenure at the company?
2. What is the process of leave encashment recovery? I had all unpaid leaves, so why do I need to pay for the 10 days?

Please answer my questions as 40k is a big amount for me.

Medical Leave and Salary Regularization

You have remained on medical leave for the months of April to June, rejoined on 1/7, served for, say, 9 days, and left the organization.

1. You have remained in the organization up to March '15 and taken medical leave during the period of April to June (say all three months). Since you have submitted (hopefully) medical documents, the leave should have been regularized as salary with medical leave or leave calculated for retirement benefits without salary. Whatever the case may be, the salary drawn in the month of April needs to be regularized. This might have been done upon submitting your medical documents by the appropriate authority.

2. You have joined in the month of July and served for 9 days as per your statement. Thus, you are very much entitled to a salary for these days. You have submitted medical documents for regularization to the organization during this period. Accordingly, your leave during the period of April to June should have been regularized, and you might have been informed about the regularization of the leave period.

3. In the final settlement, certainly, the regularized leave will have an impact because the HR might have worked out leave with salary for the month of April. Thus, your leave encashment and cumulative leave for monetary benefits will be worked out accordingly. Please approach your HR on these grounds so that your leave account may be set right, and you may not have to pay the amount from your pocket. Your cumulative leave for final settlement will provide a lot of cushion and help you in settling your account, provided you have served in that organization for a long period.

Best of luck...