Blueman – in the first instance the replacement of fences between individual townhouses is usually the responsibility of the Owners concerned, or of the Owners Corporation and the Owner/s if the fence adjoins Common Property, or of the Owners Corporation (O/C) and the Owner of an adjoining property if it’s a boundary fence (i.e. between the Strata Plan and the property next door).
So unless your Plan is atypical, and for some reason the fences between townhouses are shown as Common Property (i.e. thick black as opposed to dashed or thin lines) on the Strata Title Plan, then I don’t know why the Strata Manager arranged for and now wishes to pay for the fencer’s works from the O/C’s funds.
Notwithstanding any of the above, your own investigations would have no doubt revealed that a colourbond™ style fence can be installed with sloping panels to accommodate the local topography, and so there may be an “argument” that fencer shouldn’t be paid until such time as whoever it is that’s paying is satisfied with the work in its entirety.
The only problem that I can foresee, and which regrettably may be the case, would be where the Strata Manger as opposed to the O/C has simply selected a fencer who’s known to them, and without any specification or a quotation outlining the agreed scope-of-work, has just given them the go ahead.
As your Strata Manager is pushing for an approval to pay the fencer, I’m guessing that my assumptions about who organised the work is correct, and whilst you’re nonetheless correct by insisting that the Executive Committee shouldn’t approve the fencer’s payment until such time as it’s satisfied with the work, the “argument” around that position is that it may be difficult to defend unless there was an agreed scope-of-work and that either hasn’t been followed or there are defects in workmanship as opposed to just with that (scope).
It may well be prudent for the E/C to list the items that it would like to see corrected or changed, to request the fencer to provide a price to rectify those, and to try negotiating a price around that; clear defects excepted.