After reviewing and calling around several places around the valley to find a decent reputable audio shop, I stumbled onto Handcrafted. I called ahead to see if they work on Benz vehicles since Best Buy wouldn't touch my car because they don't have the proper insurance. I wanted a double Din Stereo with a backup camera. German cars can be very difficult to work on because of how their trim pieces integrate with the center console stereo and does require certain expertise.
When I arrived I was greeted by the owner, John. He was very attentive and gave me a tour of the place. Knowing that they been in business for many years, won several awards in the past and have a install bay that's clean, organized provided some reassurance that I chose the right place. So I put down a deposit to get all my parts ordered and waited until I got scheduled.
Install day: I was greeted by Nick, my installer. He was friendly and he walked around the car and told what he was going to do. Asked me where I wanted to mount my USB input and where the microphone would go. Install went smooth, everything aligned up perfectly on the trim pieces, no bulging, no rattling, no loose pieces. Backup camera worked as intended and it was professionally installed. They didn't do any workarounds as it's difficult enough to go through the existing wiring loom in the SUV's tailgate.
My ML350 is very happy it has upgraded sound with backup camera. Their quality of work shows why they are still in business and they keep having customers return. The customer service was so awesome that my roommate decided to use them as well. You may think it's expensive but keep in mind some things... Do you want a certified technician who is authorized to work on high end vehicles to work on your car or a $12/hr tech at a retail store who really doesn't care because he's just there for a job and probably can't wait until it's lunch time. I know this because I worked at one for several years. There's a reason why they don't work on higher end cars. You really get what you pay for. That saying never gets old :)