The charity, which helps families with disabled children, said that the money would enable to extend the hours operated by its helpline.
Parents call up for advice on help on a wide range of issues including education, disability benefits, health care and leisure in Brighton and Hove.
The people staffing the Amaze helpline receive more than 4,000 calls a year but the service has long been stretched.
The marathon funding means that it will now open all day during term time on Tuesdays – from 9.30am to 5pm.
The helpline is also open from 9.30am to noon on Mondays, Wednesdays and Thursdays and from 5.30pm to 8pm on Thursday evenings on 01273 772289 or firstname.lastname@example.org.