Hearing impaired mother keeps accidently turning down volume of iPhone. Does anyone know a way of stopping this?

Hi,

My Hearing-impaired mother keeps accidentally turning down the volume of her iPhone and doesn't understand that she needs to turn it back up, and can't hear me yelling, "Mum, turn the volume up!!!"... because the Volume is too low. (Can someone say "Catch 22"?)

Does anyone know a way of stopping this? It's causing enormous stress as we try to deal with her while she's in hospital and though Apple has provided many useful tools around the Volume controls, they haven't seemed to stop and think about people who don't have full control over how they hold the phone and thus... keep turning the Volume down, in reality a major accessability issue for both the Disabled and Elderly communities. I can't imagine given the other Software functions that exist around the Volume buttons that this would really be hard addition to the settings for them to include, but.....

Anyway... any help.. a case that blocks the buttons, or a hidden method, anything! I've been searching for days and days without any positive outcomes.

Thanks in advance (and in hope),

nathan