Hello!  We have a recreation center where customers can purchase 50 batting cage tokens for a discounted rate. If they paid for each token individually total would be $50 but they are paying $38 instead. In other words they are prepaying for these tokens in advance. We had used a paper punch system each time they visited to keep track of how many tokens remained.

Is there a way to credit customers for an item (token) rather than an amount. 

I know that I can use gift cards, ring up $50, apply discount of $12 for the prepayment of tokens, but at that point when the customer returns to use the gift card, they are able to use it for ANY item that we offer. I can't really control that they only use the gift card for batting cage tokens. 

Possibly the only way is internal control at the cashier level, which is fine if there is not another option.

Suggestions?