Tarjeta promocional

I had two promotional cards for the same amount on each. The first one, I used ¾ of the card, and the representative couldn't find it. So, we used the second card for less than ¼ of the total amount. Then, it occurred to me, is it possible to divide a card between two separate payments? If it isn't, I need to pay this bill out of my account and save the promotional card for later!

It sure would have been nice if the agent would have told me this, if it is the case. Because even locating the card was difficult--much less understanding if it can only be used one time. That wouldn't be fair.