For Diamond Bank the USSD code option is not yet available but an easier option is to use Quickteller which is explained here:
There are so many ways you can purchase airtime/credit at the comfort of your home or wherever you are.
This article will clearly explain how to do so as long as you have a bank account with one of the top commercial banks in Nigeria and an ATM card, then you are good to go.
The easiest method method of buying Airtime/Credit Online is through Quickteller. Quickteller is a convenient online portal with access to a lot of services including recharging your mobile phone, transferring money and making payments for various services like DSTV, GOtv, Internet Subscription and so much more.
Steps To Buy Airtime/Credit Online with QuickTeller
You can either do it with your browser on your phone/laptop or download the app from your mobile app store (Android, IOS, Windows) to your phone whichever one is convenient for you.
Go to the nearest ATM, and insert your ATM card
Input your 4-digit PINand press Enter
Select your bank account type eg Savingsor Current
Select the ‘Quickteller’ option from the ATM menu screen
Select ‘Pay Bills’ from the Quickteller menu list on the ATM screen
Select ‘Others’ for the bill payment menu option list
Enter ‘322222”as the Biller Code
Enter your Phone Numberas the Customer Reference Number and select ‘ Proceed’
You will get a display “Do you want to make this payment?” Amount Due:N1
DO NOT edit the amount to be paid
Click on “Pay amount due”
You will then get a confirmation page indicating the registration was successful
*Note that a surcharge of N100 may be applicable to each successful registration.