Total BS!
It's a mdps flexible coupling that is bad, a little rubber part that costs about $4. It's nestled inside a large electric motor, the control unit for the Motor Driven Power Steering (MDPS).
Replacement should be free (10 years/unlimited mileage), you just ask for it and they will look up and see that it's covered under a customer satisfaction/warranty extension campaign.
See:
https://static.nhtsa.gov/odi/tsbs/2016/MC-10090090-5448.pdf
Look, your dealership is incompetent for not knowing, or they are greedy little bastards that want your $400.
What is even more insulting, is the replacement procedure should take less than half an hour. So they would have charged you like $800 an hour for half hour of work, minus the $4 parts cost.
Be careful: the bastards at my dealership actually said they replaced the coupling under the free campaign, but they were just lying. They even prepared the paperwork and everything, saying they replaced it. But sure enough, they just took Kia corporate money to cover the free replacement, and didn't actually do it. I know because the problem remained after service, and when I asked them, they said they would charge me a $140 diagnostic fee to check, those m-fers. So I ordered the updated coupling (it's a stronger, stiffer rubber compared to the original) and did the procedure myself using a youtube video walking through all the steps (the mechanic was great, patiently filming the entire procedure start to finish. I think that mechanic claimed that if you know what you are doing you could do the replacement procedure in less than a half hour, which is what I think the techs at Kia should be doing it at that rate if they were honest.
here's picture of me holding the new coupling and the old, you can see how the old one is chewed up and wasn't providing proper cushioning when rotating the steering wheel. if you are handy, it would probably take less of your time to just do this job yourself using the youtube video, compared to the hassle of dropping off and picking up the car, plus waiting time for paperwork etc. And knowing the job was done right and no plugs were broken or left disconnected.
Oh, here's the youtube video, even with all his preliminary talking and things, the total time is still only 44 minutes long: