my thoughts exactly i really don't see why people have to condition their bags as such. they're perfect since the day they leave the workshops. so before anybody trashes LV again for inferior or declining quality... think again. im even surprised LV agreed to repair it.Sorry to hear your bag has problems.
Given that this is coated canvas, I wonder if the leather cleaner and polish caused problems. Treating it "At least once a month" is a lot! Could be with time the cleaner deteriorated the plastic coating on the canvas.
The canvas part of a monogram bag does not need any treatment at all (well perhaps a damp washcloth now and then to clean off any spills, etc.).