Poor and unprofessional service

I took a car for a service at Mercedes Sandton on 14 Dec, the car for a service. All this car needed was service. Car was serviced and all was certified as functional. I drove a car but before I got home the car was showing a battery light and shutting down. I managed to take the car to Constatia Mercedes Benz where I was told the battery was not charging. Sadly I'm required to pay for diagnostics again. Logically if the alternator is not charging this started at the Sandton workshop as the car never ever showed such signs. We don't except such challenges from the brand being Mercedes and one may have to request proof that both the alternator and battery were not tampered with.