Brake caliper fixed

Hello together. I just picked up my G after two weeks because of control chain changes from the workshop. During the test drive it was found that a brake caliper is fixed in the front. This was recognized by the rusty brake disc inside. I noticed 2-3 weeks ago that he pulls something aside when braking. I pushed them however on the coarse tolled winter tires. Anyway. I would be pleased to hear your opinion: a.) The MB workshop thought one could easily continue The vehicle is well maintained. Shouldn’t the condition of the sealing cuffs have to be “visibly checked” during any inspection? The car was only recently during the (large) inspection. I actually have the regular maintenance carried out, so that it does not come to unplanned aius cases. The servo pump is only recently complete. Although I had reported to the workshop several times before that the steering support was suspended for a short time, no remedy could be provided. Of course, a lot of the pump then out exactly on the return trip from the holiday. Or is the whole mud ash located at the specialist competence of the workshop? I am already curious about your answer. Greetings Frank