5 Months Later & issues Still Not resolved

In September of last Year my C class merc began giving me a front right crash sensor malfunction light. Due to the importance of safety I took the Vehicle into Merc Santon. After having the vehicle checked it was discovered that there were some faulty sensors in the front drivers side seatbelt stalk and some other minor issues . This was all repaired Mind you at a cost of R 20 000 but i was assured the issue was resolved. I collected the vehicle and went on my merry way. A day later i noticed that the driver head rest seemed to be loose I assumed this was due too disassembly as the head rest has sensors in it that functions in accordance with the crash sensors. only to be alarmed that the head rest was in fact broken ( looking into it it was evident that plastic clips had snapped ) . Interestingly enough i received a call from Merc Santons customer care as a follow up. I informed them that i was not happy with the work done & wanted the issue resolved. They informed me that they would get my service consultant to contact me immediately to asses the issue. This CALL NEVER CAME, i followed up repeatedly with calls and never got feedback. I eventually drove too santon so that i could physically be there on two separate occasions. The first time i spoke with Derik my service consultant, I was not happy with his excuses & reasoning for the damage. He eventually on the second occasion brought out the service manager Andrew who assessed the vehicle. Andrew then asked if they could remove the head rest so it could be assessed & the problem solved. ( this occurred in October of last year ) I was happy with that as i felt something was being done about it. As a point of information all of these items play an integral role in the safety of the vehicle linking to airbags etc. after this I made repeated phone calls to Derik to find out what was going on many of my calls were never returned. Those that he did answer he had to get clarification from Andrew and promised to call back ANGAIN no return calls. Finally in December I grew tired of all the back and forth with Derik and went in to have a sit down meeting with Andrew, he was extremely apologetic regarding the situation and the lack of urgency displayed by my service consultant. Andrew assured me that he would be taking this over and i would deal directly with him. Granted this then hit the end of year stagnation that is Christmas / New Year i accepted this. The new year arrived and I called Andrew who is far better at returning calls & explaining the situation. However the excuses are mounting , the guy who has the keys to the store is off , then he's sick, then he's unavailable. These all seem very unlikely excuses. I have been driving a vehicle without a driver side head rest for over 2 months now all posing a huge safety risk. Question is where too from here ? will they ever get this right?