When we divorced, we agreed between ourselves on the amount of child maintenance. Now it falls far short. Can it be changed?

Yes; the court can amend an agreement on child maintenance even if the agreement says otherwise. The Syariah court has power to vary the terms of an agreement on the custody or maintenance of a child where the change is reasonable and for the child's welfare. Maintenance is the child's right, so the parents' agreement cannot shut out the child's needs. Prepare evidence of actual spending now: school fees, transport, food, medical care and special needs. Add what you know about your ex-husband's income too. Before going to court, try talking first. The Qur'an teaches that decisions about a child, such as weaning, are made “by mutual consent and consultation between the two” (Surah al-Baqarah 2:233). If the talks fail, file an application at the Syariah court. See child maintenance.