Source for metal tire valve stems

Our Chateau came with valve extenders on them. During our walk through, I noticed I could not see one and they said they would fix it. Forgot to check it before we left. Noticed when we were home that I still couldn't see it. Made an appointment and took it in for them to fix. They said that they had just fallen loose. They were the flexible kind. When I left, they were good to go. Last trip I noticed that I couldn't see them again. Took it in this week to have them fix it again and install some items. Got a call from the service tech asking about the stems and if they were after market or not. I told her no and she said that they would claim it through warranty then. She showed me the extenders and they were fraid a little on the wire hose part near where they screw into the valve. If they brok all the way, that could of been bad. I asked about total metal extenders and she said she wasn't sure if the manufacturer would allow that or not. But she would check.