No offense meant whatsoever. I'm not jumping you personally for your thoughts, comments or opinions in particular. On the contrary, I'm simply looking at these particular issues in a positive light and expectation.
Cables stretch with heat and usage. If they weren't improperly adjusted outside of specifications during the assembly process and left the factory this way, they'll quickly become out of adjustment. As in your suggestion of, 1400 km's. If they had a bad batch of cables for some reason, it will happen with the specific 30N's in which they were installed. Neither of which you're or I are personally in control of.
@XxSamu93xX didn't reference anything wrong with 5th and 6th, just 1, 2, 3, & reverse engagement. This alone leads me to believe, the cable and linkage adjustment are at fault. Engagement of 1 ,2, 3 as well as reverse, utilize one of the the two existing cables.
I understand it's easy sometime to be disgruntled and upset about the way things have gone. However, it doesn't mean these issues are happening with every i30N on the road. As a matter of fact, the vast majority of owners, haven't had the issues. Those who have, let Hyundai diagnosis and repair the issue/s successfully. Those owners are happy with the result, outcome and are still driving the car daily.
I respect your personal choice to turn the vehicle back into Hyundai but it doesn't mean I agree with everything your alluding to necessarily.

You have your reasons and they're valid, especially more so to your personage. However, not everyone thinks alike.
Sometimes
we get the pig in a poke, everyone does sooner or later the older we are and more cars we purchase. I've had my share as well. It's simply not about sharing the our complaints or ill feelings. It's more about how each and everyone of us personally handle and recover from them. Meaning, with a positive thought process, attitude and moving forward confidently, accepting the way things are. Not how we personally want them to be. Life just doesn't work this way.
Worrying about these issues or any for that matter is useless. It doesn't affect a change in the status, the way the issues are being repaired or the probable outcome. We simply aren't in control of them.
Frankly, I believe Hyundai's reliability is excellent. There is no reason exacerbate someone else's personal feelings or our group concerns, over known/unknown
possible issue/s.
Forums and web specific pages and groups, focus complaints from those
who feel, there is an overall issue with their personal quality of life or desires. Doesn't mean it is necessarily so or true to form. It can be seen everyday with minority groups on the Internet. These groups, are yelling the loudest about their particular personal interests, feelings, desire and complaints, valid or not. They simply aren't speaking for the majority and the same goes on this forum as well.
Hyundai will deal with the issues, one way or another. I don't wish anyone ill will, especially Hyundai. If there is a overall manufacturing issue, I believe Hyundai will find it and make the necessary adjustment to the assembly process.

There's no conspiracy and certainly no purposeful issue/s, that aren't repairable.
I simply choose to look at and pass on a positive perspective to someone within my scope of knowledge. Rather than a negative or pessimistic one. The same here with this issue/s or with anyone personally. Lets just say, I'd rather reflect and dwell on the brighter side than the darker one. Passing on good will, rather than a poor one.
I'm not ignoring anything either. I'm just looking at it with different set of eyes. With all the complaints, there is always a good side. Sometimes we just need to be patient, stop trying to control everything and let the happen.
Please excuse and I apologize for the long winded response! Merry Christmas!
Cheers