When you say ‘we’, what percentage of the owners are you talking about?
I went through something very similar a few years ago. Ultimately we ensured enough people had paid their fees to be able to out-vote the current Directors, we then convened an EGM (rules for doing this will also be in the Memos & Arts and must be followed to the letter) and removed the existing Directors and appointed new ones. It was actually fairly painless in the end, though that will come down to how engaged your group of owners is.
If this is what you want to achieve I would not bother getting into whether the existing AGMs are valid or not as that could take years to argue and might require going to court - just get yourselves paid-up (and confirmed in writing) then replace the Board. If it turns out the fees are over the top you’ll be in control and can stop the waste and perhaps lower fees for next year. Although having read many of these threads on AAM I would warn that you will most likely discover the fees are not that crazy, OMCs just have much bigger overheads than most people realise.