It pays to check up on things

My mother‘s 95th birthday is coming up in December, and I’m going to be visiting her in Oxford for a week. This morning I went ahead and booked the flights and rental car. I priced it out at several websites, and the cheapest was United Vacations. (I was committed to flying on United, because I need a couple of thousand miles to lock in MP Premier Exec status next year.) I wanted to arrive in London relatively early, and so I chose a SFO-ORD-LHR routing. Everything went through just fine, and soon afterwards I received the detailed itinerary.
They’d booked me on UA906 connecting with UA931, which gave me just 40 minutes to make the connection in Chicago. We’re talking about Chicago in December, after departing from SFO, the airport with the worst on-time record in the US. On top of this, I was planning to check my bag through from SFO to LHR, and I was hoping that it would arrive with me.
On the other hand, the system wouldn’t have coughed up this flight pairing if it was out of policy, would it?
This evening, I decided to call United, and after wandering through a voice-recognition call tree, I got to an agent and explained my concern. “Let me look that up,” she said. “Nope, that’s wrong: you’re supposed to have an hour and 15 minutes for an international connection.” And in a few minutes she’d switched me onto an earlier flight, given me the same seat I’d had before (after confirming my preference), double-checked that the transaction wouldn’t trigger a change fee, and emailed the revised itinerary to me. I’m now on UA972-UA928 eastbound, and UA931 westbound.
Decisive, courteous, knowledgable [UPDATE: Or maybe not – see Cranky’s comment below.]: everything one hopes for in a customer service representative. Thanks.
P.S. I’m a bit particular when it comes to seats. In the northern hemisphere, I always go for a port window eastbound and a starboard window when I’m flying west. I like to look out of the window without getting blinded or fried.