Another member who has professional experience with i30s might say different - maybe they changed things between MY (Manufacture Year - the 'spec' the car was fitted to) but I doubt it.
So I respectfully suggest that the places you contacted - either a) mis-understood (clearly one did) you're query; or b) may not know *&^^
I am pretty sure there are only two types of clock-spring - one for CC and one that isn't - as you have CC therefore the clock-spring shouldn't be an issue.
I might be recalling incorrectly but IIRC the wiring from radio to dash side of clock spring is fitted in all models (irrespective of wheel controls being fitted) - i.e. not wiring difference there.
What should only be needed is the 2nd & 3rd items on
elantraelite list - as you can see there is 'wiring difference' (so they didn't technically fib) as the cable in the actual steering wheel needs to be replaced... from one that only plugs into the CC switches to a Y cable - wow such a huge difference
If you want to get it done by dealer - I would try Indooroopilly or Moorooka Hyundai. Though it might be useful to call in for a visit - so you can see if they are getting it. However I would suggest if you can source your OEM parts from ebay and/or wreckers (if you haven't already) it could be significantly cheaper that getting them through the dealer.
If you can't find an audio control fitting how-to here - then ones for fitting CC buttons into the wheel will do just as well (the section dealing with the steering wheel) excepting, of course, the clock spring fitting which you won't need to do.