Theft from vehicle and No response!!! Very poor

I have always had good services with S N j Fitment center barberton mpumalanga but unfortunately not the last time when my vehicle was there.. it was picked up with there tow truck/flat bed and taken to there workshop where it was serviced and had a check up...and on the 17th of September i went to collect my vehicle,where it was park in the street with the passengers door unlocked in the street with people walking up and down.. i got my keys and drove off and discovered my passengers door was unlocked so check the car and discovered my JBL speaker was missing from my vehicle I immediately phoned S n J fitment center where I spoke to one of employees and then the owner where he said he will investigate it and u should phone him Saturday, But no response i didn't receive any calls and then i phoned them on the Monday and still nothing was sorted out or investigated and up and till today I'm still waiting for them to get back to me... I'm so unhappy with poor response or sorry no response still...