My hearing aids have been back to the manufacturer 4 times within the past year between the 2 of them at a cost of more tha $1000, not to mention the inconvenience.
The issue in my case was not wax, it was the microphones, something which I never paid much attention to. Believe me, I now pay a l lot more attention to those 4 little openings for the mikes with my cleaning brush.
I recently had the vacuum treatment, but it was too late in my case. The vacuuming took 5 minutes at most. Not worth $100 by itself - especially if you brush the openings every 2-3 days. But I don’t know what else his service includes. I’m generally a believer in preventive maintenance, so maybe it’s worth it just to avoid the inconvenience of being without your aids for a few weeks. But debris around the mikes is just one problem. The other is moisture, which is probably the bigger problem. I’d ask him if there’s anything he can do about that or your aids might be going out regardless.
What surprises me most about this conversation with your Audi is that your aids are apparently only 6 months old. Correct? So they should be in a period when they’re covered for service (loss, damage, repairs) for either 2 or 3 years. Is this your situation? If this is the coach, your Audi should be coaching you on how to do your own preventive maintenance and cleaning with the equipment which the manufacturer provided for this purpose. The Audi shouldn’t be trying to extract more money from you at this point. I wouldn’t pay anything during the period when your hearing aids are covered fir service/repairs. And I would work on establishing good habits of cleaning and maintenance.
Good luck.