W204 C180 Executive SE 2013 Automatic / COMAND NTG4.7 and Morel speakers fitted by www.comand.co.uk
Essentially it's an oil and filter change, plus some additional checks.
Can be done by an independent, or by an MB dealer - some MB dealers have special rates for cars older than 6 years, so the dealer option isn't always prohibitive.
But it should be someone that knows the car - the oil type has to meet the relevant MB spec sheet.
The services alternate between A and B - so next time it will show 'Service B'. This is still an oil and filter change but it will cost more than an 'A Service' because of the additional checks included in the Service B schedule.
But there are also other items that may need doing, which are separate to the A and B services - e.g. spark plugs change, gear oil (or ATF) change, air filter, fuel filter, cabin filter, brake fluid change, engine coolant change... these all depend on when was the last time these were done. If your service book doesn't say when they were last done, the general rule is get them done anyway, just in case...