As long as txn is successful oxigen virtual cards are best. but if by any chance txn failes then money gone.
same happened to me. I tried to add 100rs in freecharge using oxi vcc. txn failed money deducted. oxigen agents are so poor. worst customer service. first they said within 7days automatically will come to rbl funds . did not come.
then again raised issue they said within 10days refund will come. again did not. then again they said rs100 is unsettled payment and will be refunded only after 30 days. 40 days over no refund. the worst vcc and customer ever.