GWM Edenvale staff will take stuff from your car

My vehicle went in for a service at GWM Edenvale on Wednesday, 20 December. Someone took my Monster Energy drink without my permission. The energy drink was securely stowed in my centre console. Whoever took it, drank it, spilled some of it on my rear seat and left the bent empty tin under my passenger side seat. This is unacceptable!! I have tried to reach out to the dealership in various ways, sending emails, leaving messages for the dealer principle but still no joy. I am extremely upset!