I have had my sonata in at dealership for same repair numerous times. My complaint on work order is front susp. makes a clunking noise and steering feels lose, drifts/wonders worse at highway speeds. Every work order they replace front sway arm links and check over subframe/bolts under warranty.
Steering still feels lose and within a month or so clunking sound gradually returns making drift in steering worse! It's to the point where I will not drive with my grandchildren in car. anyone have same problem or solution ?

 

Sounds to me like the bushings and possible tie rod needs to be replaced. Sometimes you have to tell them what you think for them to look at it, makes me wonder if they are taking it out on the highway where you feel it most. I would demand them to look further an say they will be resposible for mis-diagnosis if you get into a accident because of it.