Is it possible to edit payment information?

I think that this is not possible, I made some tests and though you are able to edit the submission it is not possible to edit the product already purchased since your customer has already paid for it.

The only way to update payment info would be submitting the form again and purchasing a product again filling the form with the proper info. 

If this is not what you're  looking for, please provide us a bit more and we will be glad to help you.