The elderly woman looked very sweet when she walked up to the fuel center kiosk where I was working. She was certainly old enough to be somebody’s grandma. Her hair was totally white and longish and curly. She wore eyeglasses and conservative clothes.

She had some questions about her reward points. She thought she’d get 20 cents off each gallon of gas she purchased, but she wasn’t sure.

I scanned her rewards card and pulled up the loyalty balances screen on my POS (point-of-sale) system. I showed her she’d already earned a 10-cents-off-per-gallon reward this month, and she still had a 10-cents-off-per-gallon reward from last month.

So I get 20 cents off per gallon? she asked.

Well, no. I explained she could use one 10-cents-off-per-gallon reward now and use the other 10-cents-off-per-gallon reward later. That wasn’t good enough for this customer. She wanted 20 cents off of each gallon of gas she bought today.

I explained to her that the rewards program didn’t work that way. The points don’t combine, I told her.

She was angry by then, even though I was working hard to remain calm and polite and even friendly.

What do you mean they don’t combine? she demanded.

Well, they don’t combine, I said again. I knew I was repeating myself, but I wasn’t quite sure what other words to use to explain the concept of “don’t combine.”

What do you mean they don’t combine? she demanded again. She was growing increasingly agitated.

I tried again to explain, this time using different words. I told her she could get 10 cents off each gallon of fuel she bought today and she could get 10 cents off per gallon of fuel she bought on another day, but she couldn’t get 20 cents off per gallon today by putting her rewards together.

She was still angry, and I could tell she didn’t understand why I wouldn’t give her 20 cents off each gallon of gas she purchased. Obviously 10 + 10 = 20.

I refrained from telling her I didn’t make the rules around there. I refrained from telling her that the corporate office decided how to run the reward program with no input from me. I refrained from telling her that if there were some way—any way—to combine her rewards I would have done it in a heartbeat in order to end our interaction. I simply remained calm, polite, and firm that it was impossible to combine her rewards as she wanted to do.

She finally stepped away from the kiosk and went over to pump 8 to fill her tank and probably complain about me and my arbitrary rules.