You can buy discounted g v of MakeMyTrip & cleartrip from Amazon Itself and you can also buy Amazon Pay Voucher from Amazon all these options will earn you 5% cashback+ discount on vouchers. You can directly book train tickets on Amazon through Amazon Pay GVs and in addition it will save you railway surcharge of 1%+GST charged on direct card payment. Though I have always used Amazon through GV for train booking but not used MMT and cleartrip for train booking if going for these please try with small amount vouchers first.