Theft of car parts by RAM when vehicle entrusted to them for servicing

Hi, I had sent my vehicle prior to the holidays for servicing, when i fueled up the night i was leaving for holiday i asked the petrol attendant to check my oil and water when i went in front of the open bonnet i noticed that the cover on my engine head was missing, i looked further and noticed that the oil cap on the engine was loose and the were loose parts and exposed wires and i know for a fact RAM was last under that bonnet!!, i have been sending my vehicle to the dealership for servicing and never experienced this horrible service before, the only reason i sent my vehicle to RAM is because the service warranty expired and RAM had posters everywhere. When i approached them about it the Manager told me there is nothing he can do and put the phone down on me, be careful when taking your vehicles here make sure all is in tact before you leave this place as you will be in the same position i am in currently.