Debiting customers' accounts w/o password?

[Robotech_Master]

Hi. I work for a small webhosting firm, and probably don't know as much about OS Commerce as I really ought to.

 

One of our customers is asking me:

 

We have a local customer who is selling gift certificates online.

 

There is a situation where a customer can redeem the gift certificate in the store and then we would need to cancel that amount out of their online account.

 

Without having the password to their account - how can we do that?

And I fear I don't have a clue as to what to tell him. Can someone help me out, perhaps with a pointer to whatever knowledgebase or documentation page discusses doing this?