I broke my ball valve on my Hydor Koralia 425 pump a couple weeks back. Did a search on the internet to see how much a replacement part would cost but couldn't find anything. I sent them an email via online form and they shipped me a replacement ball valve for free. 8) It took about two and a half weeks but the postage said that it was from Italy so I guess it would take that long.
Had the exact same thing happen. After 6 weeks no replacement part so called back and they sent a second. I received one package 3 weeks later and the second the next day. I asked that they send 2 each time so I now have 3 spares. They are aware of the problem and claim to be modifying the design.