The Good Guys complaint: Excessive charge of installation added on

Hello We have purchased the package of Air Conditioner and Installation Sales order S0860387257
THIS WAS
Air Conditioner $1599.00 I am ok with this
Installation $869.00 plus and add on of $550 by the tradesperson
The tradesmant visited the home at 138 Cove Boulevard River heads
He said that the quote for the installation was insufficient and the to complete the job
Would require a further $550
This is unquestionably unsatisfactory is it good ethics by the good guys

Why is the Good Guys allowing this
Perhaps do not commit the customer to this quote for labour Installation
Then have the tradesperson tack on another very substantial amount
I did initially mention that it was to an inside wall and about 4 metres travel to the inside wall from the exterior wall
The inclusions for this job should have been calculated into this quote like the pump for the evacuation of water etc
If you are going to do these quotes
Is there profit made on the labour quote by the Good guys
The labour will be about 3 to 3.5 hours

If we are committed to this by some loop hole then we will have no choice but to get the job done
But we will make sure we let people know to be aware of this issue
we may where possible not shop with the good guys again

The ideal situation would be a full refund and we will look at other options

Glenn Bowman