Hi Catzi,
There are several options.
1. Get out your magic lamp, rub vigorously whispering Azzaka continually - i.e. write a PM to him here
2. Write to your local paper explaining the situation and naming the chair lift company
3. Write to the MD of the chair lift company, copy to your local council's care support centre, politely mentioning "trading standards" and "taking proceedings"
4. Ask if your neighbour would accept the price of a paid maintenance visit from the company
5. ONLY with caution and the agreement of the chair lift owner, isolate the mains, remove the battery cover to find the size and capacity and replace it.
etc. etc.
Kind regards,
Walter