STA Stands for [expletive] Travel Agency

[UPDATE]
Halfway through writing to the STA in Knoxville, I got an email from... the STA in Knoxville. The branch manager, Scott, read my post and sent me a message explaining what had probably happened with STA here, and even researched flights that I could switch to (the lowest being $219, nice!).
[UPDATE]
My overpriced flight has still not been canceled, as the STA here is apparently the only branch that can do that, and they're dragging their feet about it. If I can get in touch with United Airlines 24 hours a day, why can't they?
[UPDATE]
It's been 3 weeks since they put it in to be canceled and refunded. I did a little internet digging and called the STA corporate office in Melbourne. I spoke with an extremely nice woman in the refunds department (I think she might BE the refunds department), who assured me I would be refunded this week. We'll see.

I hate dealing with situations that should not need my intervention, especially if they are potentially going to cost me 800 bucks.

Here's what happened: Back in May I arranged my flight to Australia through STA Travel on campus at UT. Because I didn't know when I would be returning to the States, I arbitrarily picked a date in November for my return flight, knowing that I would have to change it later on. Not a problem, they assured me. It wasn't. The problem came when I tried to add another leg to my ticket this afternoon at the STA at the University of Canberra.

I hadn't booked a flight from LA to Knoxville because it's really expensive to change the dates on a domestic flight (usually more than 100 dollars), and I figured I would just book it when I figured out when I needed to come home. The one way ticket from Knoxville to LA was about 250 dollars, a perfectly acceptable price. $850, is not an acceptable price, but that is what they quoted me. I figured I'd pay it, and then look around online to see if I could find a better deal, and then cancel with STA. I should have checked online first.

The most expensive way I can find to get from LA to Knoxville is 609 dollars. Cheapest? 260 dollars.

I trotted back to STA to tell them I needed to cancel my flight, to which they said it was a non-refundable flight and that there was "nothing we can do, sorry." They couldn't even switch my flight to another carrier. Now, correct me if I'm wrong, but isn't this something I should have been informed of before I shelled out 850 dollars?

Frankly, I felt like I was being screwed over, so I called United Airlines. Two different representatives told me that they don't even sell "non-refundable" tickets and that they could refund my money directly after they received the payment information from STA.

Back on the phone to STA, I explained the conversation I just had with United. Their reaction? "We'll call you back." About 15 minutes later they call me back, and suddenly they are able to change the flight and carrier. "I found a cheaper flight for you!" the girl told me, as if they were doing me a favor. At this point I'm so disillusioned with STA that I told them that I no longer needed the flight and needed it canceled. I don't mind collecting my bag and checking in at the airport again if it's going to save me 600 bucks. I've been told that they're going to contact their United representative and get back to me tomorrow. I'll make sure I post updates.