This has happened to me with my Capital One card!! I got a letter last week telling me my card that had a %9.9 was now going to be a %15. I called to ask why and they said they were raising all of the %9.9’s to %15 because of the market.
They tried that with me too. I told them where they could stick their rate increase. I can’t use their card anymore, but I’m paying off the current balance at the old rate. Just as well, I needed a boot in the butt to break me of some old bad habits anyway.