I have a feeling that under the Fences Act, the wall is jointly owned by the people on either side of it – but that might not apply here.
However, if the committee insists that the strata schemes owns the wall, then they have to fix it – that is their legal responsibility.
Now, if they still drag their feet even after they have been told this, point them in the direction of Section 232 of the Act which covers failure to fulfil responsibilities.
Then it’s down to whether or not they want to do it the easy way or the hard way – but they’ll have to fix it, either way