I think right now you are too predictable. You are usually asking him for his confirmation on his plans. Well change that by no longer asking. Make your own plans. And if yours are set when he calls oh well. He refuses to plan ahead in order to mess you up. Well if you call him and try to make plans say I want answer by so and so day and if nothing then go ahead with what you want to do. If he should call when you are already on your way to do what you had planned...oh well. you tried at the beginning. You can simply say I know you feel bad for not getting the kids and I'm on my way some where. Maybe next weekend when you want to see them you can let me know by Thursday what your plans are for friday.
Don't try to accommodate him any longer...you've been doing that with him ending up not respecting your schedule. Do the opposite by not being available and sticking to your own schedule. Don't be so accommodating.
