I've contacted Corsair twice, and their customer service and support are absolutely terrible. The first time, they said that They need to know exactly when and which retailer I bought my LL120s from so they can replace it. If you don't have proof of purchase from a retailer, Corair will pretty much tell you you're out on your own. This way, they don't have to deal with many RMAs at all.
Second time I emailed them telling them that I have owned several fans that all have had this issue, and of course I heard absolutely no reply whatsoever.
This is embarassing, the company is supposed to try and help us out, yet they will do whatever it takes to not refund us or even help us really.
I have had to replace 4 fans so far. I have narrowed down which ones are the problem ones and replaced them each time. It sucks because my build is in a Mini ITX case, and it's a lot harder to work with.
I really would buy fans from a different company, it's just unfortunate that Corsair makes the best looking ones on the market so far. I hate this so much.