Nobroker Technologies Solution Pvt Ltd - unnecessary charge

I did a transaction to pay society maintenance fees by using nobroker app. The transaction was for Rs *****/- and they were charging Rs *** for this transaction. But they had my money for * days and transaction declined by the company and refund *****/- but not refunded ***/- Rs. I have written many times to the company for refund but they are justifying this charge as their service charge but if the transaction not done successfully then why they are charging for it. Request to help to refund my money which charged unnecessarily.