Hyundai iLoad 2014: Gearbox whine

I am the unlucky owner of a 2014 Hyundai iLoad, which began to develop a gearbox whine late last year. It was booked in to the dealer in January to have a logbook service and the noise investigated. The verdict came back that it was a faulty thrust bearing and the complete clutch kit/dual-mass flywheel would have to be replaced at an approximate cost of $6500 as it was classed as a consumable.

I duly investigated further and found a reputable clutch and gearbox workshop that could do it for $3000. After the workshop began to replace the clutch I received a phone call from the workshop proprietor asking why I was replacing a perfectly good clutch? I said Hyundai had diagnosed it as a faulty clutch, but he told me the input shaft had too much play in it, and he thought there was a gearbox issue.

I now have a perfectly good secondhand clutch in the garage and the same whining gearbox. In July I booked the van in for another log book service and let them have another go at investigating the whine. This time they told me the gearbox is low on oil and has the wrong oil in it, and there's metal shavings present, and I should take it back to the clutch workshop because they put the wrong oil in it, and it's not covered by warranty.

They recommended the clutch be changed, which I did, and I believe they should have taken an oil sample when I first reported the whine.

Where do I stand considering I have a paper trail that says a wrong diagnosis initially, I followed their recommendation for a new clutch kit (although not Hyundai's own clutch kit, which has no warranty any way), only to find the original problem still exists?