I like the suggestion, not sure how the grouping would work that that unless he added a third type between prefix and suffix, VA wouldn't know that the first suffix was complete, I think.
Not played with wildcards much, maybe a way to use them and pull the info between?
Another suggestion to think about. Have the prefix as your example with the question, the suffix be the type, like SRV refuel, and when triggered, have VA ask for more info (basic, standard, premium) in a separate prompt. I think you can capture all three in variables, and then process what is needed from the inputs.