How can a mother get child maintenance paid regularly every month when the father pays haphazardly even though he is in a paid job, out of spite, paying late, and incompletely?

She can open a file at the bailiff's concerning the maintenance debt, and request an order obliging his employer to deduct the child maintenance from his salary every month, and transfer it to her. She can also request that back maintenance owed be deducted from his bank account, if she knows with which bank he has an account,even if she does not know the branch.