Right ok. You don’t need to worry about court yet.
This is what you do. Sit down and work out what sort of a contact schedule will work best for your DC. For example, every other weekend, Friday at 6pm until Sunday at 6pm plus one midweek overnight. This is just an example, you need to tweak it to fit in with what activities your children have at weekends/during the week etc. Then you need to think about how that fits with your work schedule, and his work schedule. Does he work weekends? If so there’s no point offering him weekend contact. If his work schedule changes the. He will get notice of that work schedule. He should provide you with that schedule when he gets it and arrange contact with you (that means he asks you if it’s suits- he doesn’t just tell you it’s happening). Once you have worked out an idea of a schedule that will work you either email or text him (it has to be in writing) telling him that a fixed contact schedule is in the children’s best interests as they are being upset by the uncertainty of when they will be seeing their father and being let down all the time. Tell him that you propose the following contact schedule, then add the schedule, ask him to consider it and then respond to either confirm that he will be using this schedule or to suggest any adjustments he needs to make to it. Then send the text/email.
Do NOT answer any phone calls from him or his mum. You need all contact to be in writing. This is for when it gets to the solicitor stage as it most likely will, he won’t like being told when he has to come for his children. But you have to offer the schedule and show them that you are not withholding contact but actually trying to facilitate it.
If he kicks off or is abusive don’t respond to anything from him. If he doesn’t respond and agree a contact schedule you don’t make the children available for contact. If he tells you he is coming for them, take them out. Don’t tell them he is supposed to be coming.
If he agrees a contact schedule then doesn’t turn up, take the DC out after 15 minutes. Once you are away from the house send him a text saying “as you have failed to collect your children for contact I have taken them out for the day to make up for the upset caused. They will be available for contact on the next date agreed in our schedule which is eg: 20th of August 6pm.”
Then don’t respond to any calls or texts from him.
Also keep a written record of every date, what happens and text received and sent from both of you etc.