That is very similar to my experience - took the best possible care and they only lasted around 10 months (this was a replacement).
I guess Re-600 is "built-not-to-last". I have HiFiMan Re-0 which I am using for 5+ years without any issues.
They should recall the RE-600's and recable them for free with the RE-0 cable. Why they refuse to do this is not surprising, for them it's better to replace and keep replacing till either your 1 year is over and or the RE-600 is no longer available and they can wash their hands of it.