Safely Remove Large Bracket Mirror which maybe hooked to wall

I have a single, oversized wall mirror—well over 4 ft by 4 ft—that was secured with metal brackets rather than adhesive. I need it taken down intact, without damaging either the glass or the wall surface behind it... (Budget: $250 - $750 AUD, Jobs: Construction, Customer Service, Furniture Removal, General Labor, Handyman, Interior Design, Project Management, Property Management)