The fact that he cancelled was what soured the moment, not the fact that u texted him.

No, it wasn't the fact that he cancelled that now has him in my phone as "rude wanker". If he indeed had the basic courtesy to do just that, I would've even seen him again. I understand that last minute problems come up which prevent them from keeping the booking. It was the fact that he hadn't even bothered to call and cancel is why he's now in my phone. If I hadn't taken the time to text him I wouldn't have been any the wiser. It's exactly as you said. I had to be the one doing the chasing, which I absolutely hate doing.
It was the rudeness and the thoughtlessness in his non-action that now has him in my phone.

I had another booking at the flat last night at 8pm. When it was five past and I hadn't heard from him I thought, here we go again, but I'll give him a few more minutes. A couple of minutes later he called out of breath apologising profusely for being late. He had to take two tubes to get to me, which I didn't know at the time, but it would explain his lateness.

The difference between these two is that one not only kept his appointment, but actually apologised for his tardiness. The other couldn't be bothered.