Increasing disrepair

Brief visit to see my elderly and housebound parents this morning. 
Dad is reluctant to let anyone work in his garden amongst his carefully selected plants, but, some parts of it are increasingly decaying and falling into terminal disrepair. Few people who claim to be gardeners know anything much about plants.
Small walls for planters that he built decades ago are falling apart. Last years leaves crowd into the corners. His massive stock of plant pots are getting blown around. 
Endless discussions on trying to get him to accept help don't get very far.  Many days work are now needed. All very frustrating.