Mercedes Benz Sandton city has ******* in their workshops

I took my car to Mercedes Benz Sandton for a service. They make you initial all these papers one of which says you confirm that you have taken all your valuables out the car, which i believe I did. When I went back to fetch my car, I drove out and reached up to get my shades and there were not there. I realised that in me taking all my valuables out there car, the last thing in my mind was to take the shades out their compartment. I drove back to complain but I was told that they will check the cameras and search the staff the worked on my car and only got the report the following day that they couldn't find anyone who took them. I asked if they could do a lie detector test but to no avail. I am very disappointed in such a big dealership that they don't even help you remember the compartments one must check before leaving your vehicle in their care. They hide behind the fact that you signed that you removed all your valuables. To me, this is unacceptable because not everyone is going to remember all the valuables from their cars. If anything, the service consultant must go through the car with you to remind you of all the places you must check because you don't take the car into service everyday to remember everything to take out.