Question of a brand changer

Hello to the municipality. Next year there will be a change of the car. Currently I drive an E350d and am more than dissatisfied with the price-performance of Mercedes. Premium are probably only the prices at Mercedes. But this should not be the topic here. My question refers to the workshop service at DS. The vehicles are, according to my knowledge, not offered at pure Citroën dealers. But what about the regular service work? The next DS dealer is But a pure Citroën dealer is in the next city. Therefore, the question arises whether a DS can also be looked after by a Citroën dealer in terms of service without losing any guarantee? How do the forum members do this here, since I am certainly not the only one who does not have a DS dealer at an acceptable distance? Thank you very much in advance.