I agree even a court order can't make him adhere to it.
However, once an order is in place, he will have been told what to do by the court. If he then refuses you have recourse to inform the court and they sanction him.
He can't deviate at will.
My order states that we must agree the full year's contact dates by the end of Jan every year. Once that's done he can't just randomly tell you he's changing it. I mean he can but you don't have to agree.
If my ex arrived to collect the kids on a non agreed date I would simply call the police and he knows that.
It gets a tiny bit easier. For example this year my ex choose not to engage with the negotiations in January. Just flatly didn't bother replying to me at all. So I've taken his silence as tacit agreement and if he creates a fuss saying he didn't agree I'll simply say... take it up with court. Explain why you refused to negotiate. I've sent him his times and if they don't suit him, cry me a river.
Grey rock approach is your friend here.
Regarding the paying for a childMinder, once he gets into court and states that he expects you to pay for that they will laugh him outside.
How old are your children?
My eldest is 10 and loathes her dad for all the above reasons, ie: he has a school residential trip coming up. He says his maintenance covers it and has refused to pay towards it. DS feels that's unfair because the maintenance prior to the trip was there to pay for cost of living and how can his dad expect me to spend it twice. I comforted DS by saying I don't mind covering it. But DS is furious at his fathers use of the maintenance as a means of control.
(DS knows about this cos his dad told him. During one of his rants about what a shit mum I am and how I'm only after his money)
In the end, it's a long road full of pain for you and the children, but these men think that no one is smart enough to see through them. My 10 year old does.
Court ordered hand overs in a public place where there is CCTV after he threw things at me one day when dropping the kids back.
Contact book so we don't speak to each other at handovers.
Separate mobile phone number I have for when the kids are with him, so he doesn't use my personal phone to send me nasty messages, I still get them on that other phone but it's only on when the kids are with him.
Separate email address for contact that I check once a week.
First step is legal advice, you get the advice and think on it. It's not a promise to take action. Just find out the facts so you can make an educated decision.