Best bet is always to get a video of the problem happening before you send it in if you can. We’ve sent things back for warranty that come back from the distributor (not any specific distro I should add) as ‘ok’ so we learned the lesson fast 🙂 If its possibly contentious or difficult to reproduce (creaking etc.) we video the issue first, send them a list of things we tried to alleviate the issue, then when it goes back we send them a link to the video to provide evidence. Its not to prove who’s right or wrong – stuff thats happening on a bike can be difficult to diagnose off the bike, its just good practice I guess.
At the end of the day the warranty is with the retailer not the distributor though, so as long as you can provide evidence of the issue (a video being the best option) then the retailer has to sort you out no matter what the distributor says, its not the distributor’s problem.