unhappy client

on the 25/09/2020, I drove my car for battery service at Renault in East Rand Boksburg, unfortunately they could not do anything about it that day, so I had to leave the car. I received a call on the 28/09/2020 around 15H00 that service was done and I arranged to pick up the car on the following day 29/09/2020, of which I did. I paid, signed off what ever that I needed to sign, they showed me where the car was parked and when I was to drive off, I notice that the bag that stays in the car all the time, that has the jumper cables, duct tape and other stuff I bought i.e tire jack and locks is not in the car. I went inside to ask about it, thinking it was mistakenly taken out by the person who was cleaning the car. To my surprise, no one knew the way about of the bag and they were boldly saying I took the bag since I signed off a consent form that I took my personal belongings out of the car. I reported this to the workshop manager and he told me to go to the police and report them there is nothing he can do from his side, he trust his employees, "it's so unfortunate that we have to deal with public, people like you" he said. That response was ******, I kept on asking him what he could have done if tables were turned, he could not answer that. Terrible service ever.......