If you can't login / forgot your password you can reset it by following the steps below:
Select the Sign in option from Viva.com website.
Click the link I forgot my password and follow the instructions.
Enter the registered telephone number and select Reset Password.
An E-mail has been sent to your registered E-mail address including instructions on how to amend your password.
Click on the link received in your E-mail.
Create your New Password and select Complete.
Enter the OTP password received in your registered phone number.
You will see the following message for successful change.
An E-mail will also be sent to your registered E-mail confirming the password change.