So I went to MB Laguna Niguel (Orange County, CA) this morning for the battery cert, no Service A.
The guy was reasonable enough and understood the difference between Service A + the battery cert, so that was good, but he insisted that there would be a charge for the desiccant cartridges (parts, not labor). I argued for about a minute, and then just told him, "OK, no thanks, I'll go elsewhere."
I looked at the Maintenance booklet, and mine says in a couple places that consumable things like fluids, wiper blades, etc. will be charged. It also lists the desiccant cartridges under "Additional Maintenance Work", for which there is a footnote stating that this is a separate invoice from Service (ostensibly prepaid-service doesn't cover these items).
So while I'd love to not pay for the desiccant cartridges, I'm also wondering why exactly we are expecting this consumable item to be free of charge to us? Nothing else is. My read of the warranty card suggests that the Annual Certification (free) is a different thing than the desiccant cartridge work; and that the recent stories that the customer support is telling people that there's a charge for parts makes sense. I kinda feel like a jerk for insisting that parts are free. Is there something magical in William's documents that clarifies this?
Also, curiously, the "activated charcoal dust filter" is a Service B item, not Service A on my 2016. The 2015 manual calls it a "combination filter" and has it at both A+B. So be aware of paying for that on a '16 if you don't need it.