Seems this is a “normal” problem. Light comes on and will stay for several
days, then go away, then back again. If this is a “normal problem”, why
should customer have to pay repair charges?
It still takes time, parts, and effort to fix. Parts obviously cost money, then if we value other people's time and effort, their working on it costs money as well. As it says, you have a 2013 Sorento. Now, I don't know how you've acquired this car, whether you got it new, or used, or if it had a warranty or not. If it was under warranty, it might have been a different story, it may have been covered, but if the car is not under warranty, any maintenance or repairs will cost you directly out of pocket. I apologize if all that comes out as brash or rude, I'm just trying to answer your question to the best of my abilities.
I have two 2013 Kia Sorento, which I had bought brand new, and they're both having the same issue. The ABS, downhill, slippery light comes on, then it goes off for about 1 month, then comes back on again. If it was a true defect, shouldn't it stay on and not come off for a whole month?