Ceiling repair in ponsonby, auckland

Hi I need help fixing the following in Ponsonby, Auckland Ceiling repair Number of cracks/holes: 1 Match paint: ✅(Yes) Due date: Sat, 22nd Jul Other Details: Newly Installed Air Conditioning Cassette Unit. Need space around the unit infilled with Gib as the front cover plate does not close the gap. Between 70-100mm wide gap on all sides, 700mm long square. Also cut out and remove water damage caused by pervious unit. Current ceiling is fibrous plaster to be patched and repaired with 13mm GIB,. Paint matching/painting optional. Needs to be done on a Saturday or Sunday as this is an operating business of private nature. Platform ladder can be provided to reach ceiling. Finished Job needs to be a paintable service at minimum, all filling and sanding completed. My staff can help with mounting the gib - if ceiling access is required as it is quite difficult to get too. Thanks