Mercedes Benz Sandton, stay away

I have never had a smooth nor satisfying service from mercedes benz Sandton My vehicle is in for service today I asked for my ad blue to be topped up and they wanted to charge me a fee of R400 for labor. This is ridiculous. Everytime i have purchased ad blue over the years they assist with no charge for a 5min procedure. Ruben was the gentlemen I dealt with, who didn't seem slightly bothered about my concern. I highly recommend staying away from mercedes benz Sandton...never a pleasant experience