We can start by opening up your billing system (we're using Charge Bee) and navigating to the Customer profile in which we want to "Add/ Edit Variables". Point and select the Variables you're interested in and Add a Label so you can easily remember them. Hit Save
Next, we can create our shortcut. Select Shortcuts and Create Shortcut. We'll select Variables and hit Save.
Now, every time we want to respond to a similar ticket in Zendesk, we just need to open the relevant tab in Charge Bee, and key in our Shortcut.