Credit Voucher.

Hi. I thought i should drop this here for advise.

I am developing this Bulk SMS software which can be downloaded and used by anyone who uses my services. Its a client software!
Now I would like to implement a payment or recharging service using a what i call a "Message Credit Voucher (MCV)". I would like this service to use the "Mobile Money Transfer Service (MMTS)" outlets in my country as payment outlets.

This is it:
A user in a remote place, wants to send messages to 2000 people, so he goes to a MMTS outlet, credits my account using the service(I have MMTS A/Cs for all service providers, they are only 2 here.)
So, after crediting my A/C, he notifies me of the credit with the "secret code given to him to give me", then, using the secret code i verify the money sent. After this, i send him a MCV,which i would like to be a combination of 3 things, the the secret code(5 characters),MMTS provider code(any number of letter characters),the money/Credits purchased(numeric).

Whoa! i dont know whether this forum will help me accomplish this!

Anyhow, when the user enters this voucher in the client software and clicks on credit A/C, this will credit or recharge his A/C and show him the amount of credits remaining.

Below is an image of that part of my app.

How do i go about this? A head start and any idea will be of great help.
Regards