Logitech's support absolutely sucks. Unless you're still under warranty, they have not replacement parts. The outer part of my mold separated and was lost. They have no provision for replacement part and they will not replace a set that's out of warranty. For IEMs that are this expensive, that's inexcusable. Hopefully you're under warranty.
That has nothing to do with Logitech specifically. It is an industry wise practise (except for less than a handful of companies) not to actually repair, but to replace within warranty. Price generally has nothing to do with it as well. IEM of other brand that is twice as expensive as TF10 get the same treatment, unfortunately.