Of the people I know who have gotten hearing aids, every single one of them was disappointed. Every single one of them still had trouble hearing. As far as I can tell, the only thing the audiologists appear to be able to be able to correct for (with current hearing aids) is "make it louder". If more than that is needed, it's a vicious cycle of taking it home, realizing it's not really helping, and bringing it back to try a new one.
The above seems to be particularly true when the hearing problem is heavily weighed towards not being able to hear certain/higher frequencies, so can "hear" people talking, but can't understand it; especially if there's any background noise at all.
I sympathize that your job was hard and that the clients made it harder. But the clients following directions and trying multiple different hearing aids ... doesn't really solve the problem in a lot of cases. Hearing aids are very expensive, far too expensive for a result of "I still can't understand people talking to me".