ODCE as stated is the best port of call. This is of course just a template and can be added to and adjusted as needed to meet your needs. Both AGM and EGM documentation is very similar.
The wording is the very LEAST of your concerns however.
Remember that you don't remove company directors, you seek to replace them.
Who will the replacements be? If your concerned about being stuck with writing one letter I'm not sure that bodes well for the much greater amount of paper work and work in general required to run an OMC.
Without committed and viable alternatives to the current directors who are ready to stand up and make a difference the EGM is a waste of time.