I have merely perused this discussion thread.
A few enquiries: for what duration have you possessed the vehicle? Have you purchased from an M-B dealership; has it been maintained by them and is it current?
I understand the vehicle is several years old, yet if it possesses a complete dealer service history, it might include their Mobilo Life coverage, which could allow you to request a diagnostic visit. I am confident that additional individuals will join, given the numerous terms and conditions; however, the primary stipulation is that maintenance must adhere to the schedule and be performed at an M-B dealership.
If that is not the case, are you affiliated with one of the breakdown services, such as AA or RAC, and do you possess home start coverage? Once more, you might be able to arrange for a technician to visit and diagnose the issue with your vehicle. If the issue extends beyond the battery and they are unable to resolve it immediately, you ought to request that they transport the vehicle to a garage of your preference.
The issue may lie with the battery, as previously mentioned by others; should you procure a replacement, verify the appropriate specifications for your vehicle (some models possess dual batteries, though I am uncertain about yours) and opt for an OEM brand such as Bosch or Varta; select a battery with a five-year rating. Although substituting the battery will undoubtedly pose no detriment, there exists the potential for other issues to be present.
To ascertain the appropriate battery type for your vehicle, input your registration number on the website provided below, navigate to the car batteries section, and it will specify the correct battery model for your car, along with a selection of compatible batteries from various brands; it is advisable to opt for one of the premium brands listed, yet it is prudent to compare prices as they can differ markedly between retailers (occasionally by as much as £100 for the identical battery!).
For instance, if a website indicates that your vehicle requires a type 019 battery, it is likely to present various options available for purchase; however, if you also explore platforms such as eBay or Amazon, or simply conduct a Google search for a type 019 car battery (this is merely an illustration and may not pertain to your specific vehicle), the results will yield numerous vendors, revealing considerable price disparities for the identical battery—thus, it is advisable to compare prices.