It does sound like more than maintenance work is being undertaken and the correct procedures have not been followed. This should have gone to a vote by the sound of it.
Our SC made a similar garden plan a while back but we did hold a SC meeting to cover off the work. It may have been pushing S.111 a tad but we got it done and saved a lot of money.
What outcome are you looking for i.e. are you now wanting to stop the work?