… convene a meeting, get the 3 spaces made legal, and move forward to the tribunal for the parking infringement.
See Kaindub’s comments below. Your development approval would have come with certain conditions and that includes the number of parking spaces for your block. Now, your local council may be OK with this change of use (because that’s what it is) but there’s every chance that they won’t be. And you can pass all the by-laws that you like, but they can’t contravene superior laws … like Planning laws, for instance.