Sorry about the title, I didn't know how to phrase it really.
I've had enough of exP and I want to say to him "give me a phone number, make arrangements that you will stick to or don't bother." but I don't know if IABU.
He expects me to ring and make all of the arrangements for his access, and if I don't then he doesn't see them. I didn't know this so I was waiting for him to contact me, and as a result DC (age 2 & 3) haven't seen him since boxing day. He won't set up a formal arrangement because "I don't plan ahead."
Last week I rang him and asked if he could see them- they were asking. We arranged for me to make the 2 hour journey (long walk, two trains, walk) to drop them off and then pick them up after because he had no money again to do the journey himself. I felt bad for DD who keeps asking to see him so I was going to do it despite it being a huge PITA for me.
Anyway, on the day I woke up feeling awful with a migraine so I rang to ask if he would meet me half way (well 20 minutes for him, over an hour for me still). He wouldn't. I offered to give him the money for it, he still said no. Then shouted at me for stopping him seeing his kids 
Then his mother got involved calling me names and now he won't speak to me at all, insisting on arranging things through my mum who is too busy to liaise between us.
He makes things difficult because he knows i'm spending time with DP and he doesn't like it. On boxing day he rang me to say he was dropping them off 2 hours early even though he knew I wasn't home and i'd arranged to get back in time for them to arrive home. I couldn't get back in time (was relying on a lift at a specific time) so he dropped them off where I was, and I had to put them in a car with no car seats in the snow, to drive 30 miles on the motorway. He didn't care at all, and in fact didn't even have car seats himself! Should point out that it's not his car, his mums, but they drive DC around when he sees them (obviously I only found this out on boxing day).
I've had enough, it costs me a fortune to do this all the time, he never takes responsibility for anything and it's upsetting the DC who already have issues after the break up.
So, am I being fair? And if i'm not, can you think of anything else I can do?