Mobikwik — Not refunding the unsuccessful amount from more than 2 weeks

I did a transaction on 17 April To AJIO from ZIP pay later ( mobikwik), since the transaction was unsuccessful then and there, it is not reflecting on the statements of MobiKwik app and thus i don't have any transaction I'd for the transaction, but now they have added that amount in the bill at the end of the billing period, and now they are asking me to pay before due date and failing to do so will effect my CIBIL score and also I'll have to pay a penalty of ₹500 . I have complained about this to there customer care 8-10 times yet there is not response .