My go-to Mercedes specialist mechanic checked out a light in my car and found two faults in the SBC brake system: C2131 Pressure Reservoir & C25D5 Hydraulics Fault. He told me of the 25 year warranty Mercedes offers, so I took my car to an official dealership who just told me that they found the reservoir fault and are working to replace that. But I don't know if the reservoir and the hydraulics are one-and-the same thing, so I don't know if both are being repaired. And also, my mechanic said that the SBC assembly is over 800k and needs to be replaced (it should be replaced over 500k he said), which the dealership didn't tell me if they are going to do because they, "have to see a code first."

What should I say to the dealership to possibly get these replaced/looked at? I'm not even sure if their technician looked at the hydraulics and/or assembly since all I've been able to talk to is the front desk/computer clerk who puts in the order. I was told that they'll replace the reservoir and will check the codes again to see if anything else pops up that should be repaired. But if nothing pops up, then they said that they would be done with the car. Anything other than that, if they don't find a faulty code, they'll charge me $275 as an inspection fee.

I'm not at all savvy with this stuff, and I don't want to start an argument over something I don't understand anyways. But what should I do if all I'm told is they replaced the reservoir without them mentioning the hydraulics or assembly?

Thanks