When to give up on a crap dad...

I'm feeling pretty down due to my crappy dad. Without having to go into everything or to bad mouth, a gist of the situation; we've not been close since I was 11, cue years of being let down etc in marvelous, marvelous ways. He's never come to visit me (I would visit grandparents etc and while there would make an effort to see him) and this year I didn't even get a text or a call on my birthday (even a late one). I've messaged him, asking if he thought anymore about visiting and he's ignored the messages (WhatsApp). Any words of wisdom?