I am using this class:
http://jimkeller.blogspot.in/2008/07/php-class-for-payflow-pro-transactions.html
I need to implement recurring billing for my client so that the amount varies for one period then others.
For example: I need to charge customer amount $500 per month. But want to give a discount of $100 for the very first month. Therefore it means for the first month he will be charged with amount $400 and for the rest of the month he will be charged $500.
Any solution for this?
If you have an actual recurring/subscription profile setup you can't charge variable amounts, but you could do that using reference transactions instead.
You would process the original amount, and then you could use that transaction ID into a future recurring payment request with any new amount. PayPal would use the card details saved in their system from that previous transaction to charge the new amount.
You would then need to build your own method of triggering those payments when they need to, so you might setup a CRON job on your server, for example, to check all your database records for payments that are due that day and trigger a reference transaction for each one accordingly.