Volunteering Incident

Today when volunteering at the hospital gift shop, there was an unhappy incident which I thought I should reflect on.

Having only one short training session and three shifts volunteering at the hospital so far, I am still not very familiar with using the lottery terminal. Of course, I can do basic transactions such as selling and redeeming tickets, but there are still certain scenarios that I am no very sure how to deal with. For example, what should the retailer do if the customer wants to redeem tickets plus buying tickets using the selection slips? This problem was the cause of the unhappy incident today.