The problem with that of course I have never known a council social services putting in a wet room or bathroom or shower, they lend you a bath lift.
Maintenance would be classed as the servicing of the equipment, a stair lift has to be checked and serviced as it has moving parts, and that would be taken on by the person who took out the loan after two years, unless he took out insurance.
Now then structural faults to the work for example a wet room or a shower if say it started leaking, the company could be held responsible because it would be expected to last longer then five years. The heater of a shower, if it needs repairing this could be deemed as being part of the service, although a shower would be expected to last longer then two years, but five years would be to long.
I suspect depending on whats gone wrong and the amount of money needed to repair it then perhaps it's time for another assessment.