I've raised £12000 to put down a deposit on a Motability vehicle.

A motability vehicle is needed to allow a brother and sister to have their independence.
Joel and Hope are siblings from Gloucester in the United Kingdom, born with a neuromuscular condition relating to the RYR1 gene. This means they have general muscle weakness. Hope is able to do small amounts of walking, Joel cannot walk at all. Both are wheelchair dependent.
In 2007, when Joel was five and Hope was three, we raised money through some very generous charitable donations, to get a vehicle large enough for Joel and Hope to sit side-by-side in their wheelchairs. Now, ten years later and with both children as teenagers, the vehicle we bought is becoming unreliable and increasingly expensive to run. There have been numerous occasions over the last two or so years where we have been stranded, unable to move the vehicle, sometimes with us unable to get the children in or out of the vehicle, due to a failure of the side lift or some other component. In addition, both children, particularly Joel, have run out of headroom in the car. They will only continue to grow.
We would like to raise money for a new vehicle. The ideal would be for us to buy another adapted vehicle outright, but the would be between £40k-£50k. A more realistic option would be to lease a vehicle through Motability but we would still need a sizeable deposit of at least £8,000. If we can raise £12k, that would allow us to have all the features we need with manageable onwards payments.