Custom customer payments

Could someone please point me to a suitable plugin.

I want to allow customers to pay their service bill online. I don’t think a shopping cart is suitable because there are no products. Each payment amount is different each time.

I need to either:
– send the plugin key info (price, customer #) from a separate system, have the plugin deal with the credit card company and then return confirmation to the original system so I can mark it paid.
– OR
– have the plugin access info from a table in a separate database (same server), do the processing then mark the account as paid.
– OR??? (suggestions)

My credit card processor is Chase.

Thanks for the help.