Need Advice on having been overpaid by previous employer

Dear Sir/Madam: Hope you are doing very well. I am Ravi Tripathi, working as a Manager at a renowned MNC in bangalore, was previously working with another MNC. With the previous MNC, I took a 2.5 months unpaid leave, due to my sickness and informed the management and HR before proceeding on LWP(Leave without pay), in e-mail. I am yet to receive the EXIT letter from previous employer, and due to error on their part, they have overpaid me, i.e. they have paid me complete salary for the duration of 2.5 months. However, I was not aware of this fact, as I do not use that particular bank account much, and the funds got utilized by my parents for my home loan repayment. Currently I am out of extra funds and they are asking me to refund a salary of those 2.5 months, which they credited to me out of their error, I do not have any part in making that happen. Can you please share your invaluable insight that whether they can do anything legally if I commit to refund the money in some months or do not refund at all? Please guide me. Thanking you in advance.! Thanks, Ravi Tripathi.