Negligent and arrogancy

I was treated very badly in this panelbeater, the work done was perfect however, i was called to collect my car only to find out that the boot is no longer working, when i asked they told me that because the boot was tempered before and wired wrongly but when i brought the car it was working perfectly so. for them to see it was wrongly wired what were they doing at the boot because the work was didn't need boot wiring? and the wheel bolt were not tighten and the 1 bolt was inside the car almost got an accident due to this neglect from them.