Economy Travelers with United Airlines reservations can enjoy a variety of refreshments, snacks, and more on board. Some of them are complimentary while others are available to purchase. The precise items available on your flight may vary depending on where you're going or the duration of your flight. Hence, for passengers who wish to buy food or drink while boarding, the Airline allows them to save a form of payment with their services.
For more information regarding the inflight services of united economy dining, you can call the customer service department of the airline. Moreover, you can also try this +1-800-865-1848, which also provides you with all the information whenever you want.