I was on the Kaitaki, on the way back from a kayaking trip in Abel Tasman, when it had it's breakdown, so I know better than anyone the consequences of these ferries failing, but the project to upgrade them was at more than 2x the original budget, and set to increase further when the new government pulled the plug.
If Labour and Kiwirail had managed to keep the project under budget, we'd still be getting the boats, but the project had blown out by more than the cost of the vessels themselves.
The whole thing is a clown show, to be honest.