I think we have been over this ground before. The advice that has been offered that the changes to the railings constitute an upgrade – which requires a special resolution – not a repair (which doesn’t).
Someone, preferably a group of you – needs to write to the EC members and tell them that they are acting outside the terms of the Act, the have no authority to raise the special levy and if they proceed with the action a general meeting will be called at which they will need to convince 75 percent of owners present to support them. Otherwise they may have to pay for the work themselves as they have instituted an upgrade for which they have no authority.
It is worth sending a letter to all owners telling them that they face either repair bills that they don’t need to pay, or legal expenses for defending either the EC against the owners or vice versa.
Communicate!