Mercedes-Benz - Terrible service. I'm without a car for over a month and you don't even care to call me back

My Mercedes SLK has been at my panel beater since 1st week November. There is a honeycomb grille ordered from Mercedes-Benz in Pinetown durban. Mercedes-Benz has no parts available. Apparently there warehouse is a mess and they can't locate the parts and there's a delay on all Mercedes-Benz spares. I've logged a complaint over a week ago and received a reference number ***1. I was told that I would receive a call with 3 days and it's been over a week. I called them today and was told that they will look into it as there has been no update on their system and that they would call me back. I still haven't been contacted and I'm without a vehicle and it's the festive season. Pathetic service for a company like Mercedes-Benz. They don't get back and they don't keep their promises.