I would email him that if the maintenance isn’t in your account within 24 hours you will open a claim with the CMS. Then do it!
Re the children. At this point I wouldn’t mud sling. It’s obviously still All new and they have enough to contend with.
Are you claiming all benefits you’re entitled to?
I have always taught my child we have to be careful with money and that means saying no to treats and other things . That in itself is an important life lesson. But don’t say because of your dad as that isn’t fair nor strictly true as arguably you could also work more hours etc…..imagi im if that’s what dad was saying to them is the reason they don’t get treats…..