I don't think that tinkering/redecorating will make any difference. The house is simply over priced in a very slow market .Your PILS do however have some options to consider if they will not accept a drop in price:
The rental market is buoyant at the moment and has gone up by 400% since the down turn ( as % of housing stock).
People who would previously have bought can't get mortgages and are turning to renting as a mid to long term solution.
I would get an agent out to advise on likely rental income and what would need to be done to get the house in letting order.
This could give them a regular income to enable them to rent a smaller property to live in.
If they are willing to consider new build properties then one of the builders would do part exchange. This would be based on realistic value of the property ( at the lower end).
They may also be able to do a private shared equity arrangement where someone buys say 75% of the property just now and the rest at a later date. Your pils would retain a share of the property . A lawyer could advise on this.
They definitely need independent financial advice about their mortgage situation and I would absolutely not offer any financial help, You will be putting your own situation at risk and not doing them any favours in the long term.
This is an area which I am very familiar with so feel free to pm me if you would like more detailed info and advice.