Billing for a second item with the original payment information.

[#1]

I send out samples with each sale, and often the client wishes to purchase one of the additional samples. They ask if I can bill their credit card; as I understand it, I do not have access to their card information.

As it stands now, I ask them to go to the store site and make a purchase for the sample, using a free shipping coupon code, as the item was already shipped to them.

The problem is, I'm having difficulty tracking whether they are actually making that additional purchase, and also getting them to actually do it. 

Is there any way to access their card information to bill the extra purchase to them myself, without their having to go onto the site to make an additional purchase? Thanks.    

[Adam7]

Thanks for posting, @rwosjo. I don't think there's a way to do that since like you stated, their billing info isn't stored. Hmm... The main issue seems like getting them to follow through on another purchase, right? Maybe you could offer a coupon to further incentivize your customers to come back and make the purchase?