I can't remember figures but my 'C' class was similar. A & B is a small service then a big one and so on. Over the 4 years or so that I had the car, it was cheaper to pay as you go rather than a service plan. Although in fairness, it was a low mileage vehicle. If the Marco Polo is bought new, you need to factor in that any failed components are covered under warranty anyway, so really you are paying for checks and fluids and maybe the odd filter.
What a service plan gives you is convenience