Okay, many has don that with out the covers, if you have a picture of the marks. Cant help if your mechanic is blind. 
Its not impossiple with out covers.
HI,
The previous mechanic destroyed the front cover, then later doing other work, damaged the belt.
the belt broke after a New km.... , the mechanic disassembled the head and half head and destroyed the back cover and other pieces into small pieces. He wanted to keep my car.
I took the car away to another auto repair shop.
This mechanic told me that he fixes the car if I have all covers to protect the belt, also to do other repair and maintenance work in the future.
I'm sorry too, but without the cover, I have to scrap it, I can't have thousands of euros in damages every few kilometers because the belt is not protected. Belt failure bends valves and breaks camshafts.
The belt must be protected with its covers.