Xp sees DS very frequently, no formal arrangement as doesn't seem necessary in our case.
But I've been asking him for a long time to give me reasonable notice if he will be coming over/collecting from school/taking him for dinner/having him overnight etc... And he just doesn't IMO.
I have no problem at all with the amount he sees him, I would just like to know in advance so I can (selfishly?) plan my own time better.
We have had a few blow ups about this over the last year or two -or rather I have - and he seems to get where I'm coming from, apologises but then nothing changes.
Yesterday I finished work about two, needed some shopping but thought wouldn't have enough time before end of school so went home, then at 3.10 get a message from xp saying he'll get DS from school. Annoying as had I known I'd have gone shopping. Then they come here (this is probably unreasonable of me but I find it irritating that he does this, if he is free to see DS then why not just take him to his? I don't need a social visit with him! But when I've mentioned this in the past he says that DS wants to see me - so fair enough really) I wasn't feeling great so had a blanket on the sofa and could barely keep my eyes open, think he felt annoyed I wasn't being good company or something though DS was happy as he came under blanket with me and we talked about his day, so xp said he'd take DS to his for dinner - fine. All I wanted to do was sleep and I was counting down the time til DS got home so we could go to bed, then I get a message at 7.30 saying 'hope you're feeling better, I'll be getting DS to bed in a minute'. 
I was fuming and called him asking what on earth was going on last I heard he was just going over for dinner! He did his usual placating, apologised though I'm not even sure he got why I was annoyed and tbh I really lost it with him and was very ranty and sweary. I feel bad about that, especially as what happened yesterday was no big deal really, it's just that I take the constant drip drip drip of little things like this and then there comes a point where all the pent up resentment about his inability/unwillingness to be clear with me about what is happening comes frothing out.
I don't even know if I'm explaining this well, still feeling bleurgh today....
Ami being unreasonable? Can take it if I am.