There can be number of reasons why you wouldn't have received the cashback credits in your Fave account -
1. The transaction is not successful
2. Merchant or the QR you had scanned is not registered with Fave
3. App is not updated to the latest version
If you have checked the above points and still haven't received the credits then raise it to us via 'Support' section on your Fave app or write to us at email@example.com.