It's no great surprise that when a company has a monopoly on a market or product that their customer service sucks. They really don't have to give a shit because what else can the consumer do? We can't buy our gas from anywhere else? We can't tell them to stick their "all-day appointment windows" up their ass. What do they care that the "operators are currently busy"? They have zero incentive to hire more staff or train them better.
Here's the biggest insult, Southwest Gas, you're worse than Comcast.