Oh, your vet works very different to mine. We can only get info via phone for something we have just been to vets for ie in this case the back but he wouldn't give advice over phone for ears regardless of how long the history of ear trouble was, we'd have to get another consultation just to make sure it was in fact ears and not back issues iyswim.
My friends dog had continual ear infections and their dog was given a GA and had ears flushed out and treatment applied whilst asleep. Seems like it would be kinder in your dogs case considering his history of ear troubles, difficulties in adhering to treatment plan due to intense dislike to having ear drops applied and the immediate problem of potentially damaging the crumbling discs further whilst trying to wrestle with him to get ear drops in if it is another ear infection.
Do you warm the drops up slightly (to body temp) before you administer as sometimes its the chill of the drops that a dog objects to not the ear drops per say.
Think I'd be looking at changing vets if I didn't think mine was been helpful.